Dual inhibition of Kif15 by oxindole and quinazolinedione chemical probes

Article abstract of DOI:10.1016/j.bmcl.2018.12.008

The mitotic spindle is a microtubule-based machine that segregates a replicated set of chromosomes during cell division. Many cancer drugs alter or disrupt the microtubules that form the mitotic spindle. Microtubule-dependent molecular motors that function during mitosis are logical alternative mitotic targets for drug development. Eg5 (Kinesin-5) and Kif15 (Kinesin-12), in particular, are an attractive pair of motor proteins, as they work in concert to drive centrosome separation and promote spindle bipolarity. Furthermore, we hypothesize that the clinical failure of Eg5 inhibitors may be (in part) due to compensation by Kif15. In order to test this idea, we screened a small library of kinase inhibitors and identified GW108X, an oxindole that inhibits Kif15 in vitro. We show that GW108X has a distinct mechanism of action compared with a commercially available Kif15 inhibitor, Kif15-IN-1 and may serve as a lead with which to further develop Kif15 inhibitors as clinically relevant agents.

Full text of DOI:10.1016/j.bmcl.2018.12.008

Bioorganic&MedicinalChemistryLettersxxx(xxxx)xxx–xxx
Contents lists available at ScienceDirect
Bioorganic & Medicinal Chemistry Letters
journal homepage: www.elsevier.com/locate/bmcl
Dual inhibition of Kif15 by oxindole and quinazolinedione chemical probes
Megan E. Dumasa, Geng-Yuan Chenb,1, Nicole D. Kendricka, George Xuc, Scott A. Larsend,
Somnath Janae, Alex G. Watersone,f,g, Joshua A. Bauerh, William Hancockb, Gary A. Sulikowskif,
⁎
Ryoma Ohic,i,
a Department of Cell and Developmental Biology, Vanderbilt University, Nashville, TN 37232, United States
b Department of Biomedical Engineering, Pennsylvania State University, State College, PA, United States
c Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, MI 48109, United States
d Department of Medicinal Chemistry, University of Michigan, Ann Arbor, MI 48109, United States
e Vanderbilt Institute of Chemical Biology, Nashville, TN 37232, United States
f Department of Chemistry, Vanderbilt University, Nashville, TN 37232, United States
g Department of Pharmacology, Vanderbilt University, Nashville, TN 37232, United States
h Department of Biochemistry, Vanderbilt University, Nashville, TN 37232, United States
i Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109, United States
A R T I C L E I N F O
A B S T R A C T
Keywords:
Kinesin
Mitosis
Oxindole
Kif15
The mitotic spindle is a microtubule-based machine that segregates a replicated set of chromosomes during cell
division. Many cancer drugs alter or disrupt the microtubules that form the mitotic spindle. Microtubule-de-
pendent molecular motors that function during mitosis are logical alternative mitotic targets for drug devel-
opment. Eg5 (Kinesin-5) and Kif15 (Kinesin-12), in particular, are an attractive pair of motor proteins, as they
work in concert to drive centrosome separation and promote spindle bipolarity. Furthermore, we hypothesize
that the clinical failure of Eg5 inhibitors may be (in part) due to compensation by Kif15. In order to test this idea,
we screened a small library of kinase inhibitors and identified GW108X, an oxindole that inhibits Kif15 in vitro.
We show that GW108X has a distinct mechanism of action compared with a commercially available Kif15
inhibitor, Kif15-IN-1 and may serve as a lead with which to further develop Kif15 inhibitors as clinically relevant
agents.
Eg5
Cells sustain life by dividing. The division process, which includes
mitosis and cytokinesis, is a logical target for cancer therapy, particu-
larly in cancer cells that exhibit growth rates higher than most normal
tissues. Chemotherapeutics that act by derailing cell division are termed
“anti-mitotics”.1 The archetypal class of anti-mitotics target micro-
tubules (MTs), which are the major component of the mitotic spindle,
the apparatus that segregates chromosomes during mitosis. Paclitaxel,
the best known MT toxin, is a blockbuster cancer drug and is commonly
used to treat a wide range of tumors.2 Despite the success of MT-tar-
geting agents, they commonly cause side effects (e.g., neutropenia,
peripheral neuropathy), reflecting the widespread importance of MTs in
cell function.3
mitotic spindle.4 The first clinically targeted kinesin was Eg5, a kinesin-
5 family member that slides pairs of anti-parallel MTs apart to drive
centrosome separation, which is the key step in the establishment of
spindle bipolarity. When Eg5 is inhibited, the spindle fails to bipolarize
and instead forms a monopolar spindle.5 A multitude of kinesin-5 in-
hibitors (K5I) that act via distinct mechanisms have been developed and
characterized.6 All clinically relevant K5Is are allosteric inhibitors that
bind near the Loop5 region of the Eg5 motor and decrease its affinity
for MTs.7 While K5Is show robust anti-proliferative activity in cell and
mouse tumor models, they have largely failed in the clinic.6 The un-
derlying reason(s) for K5I failure remain unclear, but one hypothesis is
that there are cellular mechanisms that can compensate for a loss of Eg5
activity.
To minimize collateral damage, next generation anti-mitotics target
proteins with mitosis-specific functions, such as kinases (e.g., Aurora
and Polo kinases) and MT-dependent motor proteins (i.e., dynein and
mitotic kinesins) involved in the assembly and remodeling of the
Consistent with the idea that an auxiliary spindle assembly me-
chanism can substitute for the Eg5-driven pathway, a second mitotic
kinesin, Kif15, can promote spindle assembly in the absence of Eg5
⁎ Corresponding author at: Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, MI 48109, United States.
E-mail address: oryoma@umich.edu (R. Ohi).
1 Current address: Department of Biology, University of Pennsylvania, Philadelphia, PA 19104.
https://doi.org/10.1016/j.bmcl.2018.12.008
Received 19 October 2018; Received in revised form 30 November 2018; Accepted 4 December 2018
0960-894X/©2018PublishedbyElsevierLtd.
Pleasecitethisarticleas:Dumas,M.E.,Bioorganic&MedicinalChemistryLetters,https://doi.org/10.1016/j.bmcl.2018.12.008

M.E. Dumas et al.
Bioorganic&MedicinalChemistryLettersxxx(xxxx)xxx–xxx
Fig. 1. GW406108X (GW108X) inhibits and displays preference for Kif15. (A) Structure of GW108X. (B) Concentration response curves (CRC) generated from the
ATPase (blue line) and MT gliding (green line) assay. CRC from the ATPase assay was developed from 10 concentrations from 30 to 0.001 µM. Each concentration
was repeated in triplicate. CRC from the MT gliding assay was developed from 12 concentrations from 10 to 0.2 µM. Error bars show SEM. (C) Representative
montage of a fluorescent MT in a gliding assay with Kif15-N700 with DMSO (top) or 10 µM of GW108X (bottom). Numbers indicate time in seconds after initial
frame. Scale bar, 5 µm. (D) Representative montage of fluorescent MTs from the double wash out experiment. Numbers indicate time in seconds after initial frame,
which are not the same MT for each condition. Scale bar, 5 µm. (E) Percent inhibition of indicated mitotic motors treated with 30 µM of GW108X. n > 20 for all
conditions, ****p < 0.0001, **p = 0.0074. (F) Max intensity z-projections of TP53−/− RPE-1 (left) and KIRC-1 (right) cells treated with DMSO or 25 µM GW108X for
24 h and stained with antibodies targeting Kif15 (grayscale and red), tubulin (green) and DNA (blue). Lookup tables (LUTs) for grayscale, red, and green channel are
scaled identically. Scale bar, 10 µm. (G) Quantitation of % of pre-anaphase structures in TP53−/− RPE-1 and KIRC-1 cells treated with DMSO or 25 µM GW108X for
24 h. Each condition was tested in triplicate and n ≥ 100 cells per replicate were counted. Errors bars show SD. (H) Quantitation of Kif15 on metaphase MTs in
TP53−/− RPE-1 cells treated with DMSO or 25 µM GW108X. Shown are ratios of Kif15 fluorescence intensities to tubulin intensities. Box-and-whisker plots describe
the median value as well as the 10th, 25th, 75th and 90th percentiles. ****p < 0.0001. n ≥ 25 cells from triplicate experiments.
2

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activity.8–11 The importance of Kif15 in K5I-resistance is highlighted by
our recent discovery that deletion of KIF15 prevents the emergence of
K5I resistance in cultured cells. This finding raises the possibility that
therapies targeting spindle assembly will not be efficacious unless Kif15
inhibitors are also included.10
cell line adapted to survive in the presence of the kinesin-5 inhibitor
STLC. Cancer cells can acquire resistance to K5Is, and these K5I-re-
sistant cell lines (KIRCs) rely on Kif15 to build a bipolar spindle.8–11 We
generated the KIRC-1 cell line as a clone of TP53−/− RPE-1 cells that
adapted to the presence of 10 µM STLC (see Materials and Methods).
Without further perturbation, KIRC-1 cells exhibit ∼50–60% mono-
polar spindles, consistent with previously published K5I-resistant lines
(Fig 1F and G).11 Confirming that Kif15 is essential to complete cell
division when Eg5 is inhibited, depletion of Kif15 from KIRC-1 cells by
RNAi blocked bipolar spindle assembly; 99% of Kif15-depleted KIRC-1
cells contained monopolar spindles, compared to 65% in control siRNA-
transfected cells (Fig. S3D and E). To test the effects of GW108X, we
scored monopolarity in KIRC-1 cells treated with 25 µM of GW108X (in
the presence of 10 µM STLC), and found that the compound increased
We set out to identify chemical scaffolds that target Kif15 as a
starting point for tool compound development and drug design. We
screened the GlaxoSmithKline Published Kinase Inhibitor set (GSK
PKIS) and identified two oxindole compounds that inhibit Kif15 ATPase
activity. GW406108X (hereafter GW108X) and GW305074X (2) in-
hibited Kif15-N420 ATPase activity by 76
3.6% and 90
5.3%,
respectively (Figs. 1A, S1B, and S2A). Both compounds contain an
oxindole core and a halogenated phenol ring on the right-hand side of
the molecule. They differ most at the 5-position of the oxindole, with
GW108X being an acylfuran and 2 being an iodide. Oxindoles are a
class of privileged scaffolds that have been frequently used as starting
points for kinase inhibitors, but this scaffold has previously been used
to generate a myosin V inhibitor.12 GW108X and 2 were first described
as potent c-Raf1 inhibitors and have since been extensively character-
ized by GSK, with GW108X reported as being a promiscuous kinase and
GPCR inhibitor.13–16
the percent of monopolar spindles in KIRC-1 cells from 49
95 3% (Fig. 1F and G). The ability of GW108X to block spindle as-
sembly in KIRC-1 cells was dose-dependent (Fig. S3F).
4% to
In KIRC-1 cells, Kif15 is required for spindle bipolarity (Fig. S3D),
but we cannot exclude the possibility that the increase of monopolar
spindles in the presence of GW108X is not due to mechanisms beyond
Kif15 inhibition. Since GW108X is a broad-spectrum kinase inhibitor, it
is possible that a block in spindle assembly is partly due to co-inhibition
of a mitotic kinase(s). Importantly, such kinase inhibitor activity is
tolerated in RPE-1 cells, as spindle assembly is not prevented in the
parental cell line. In HeLa K5I-resistant cell lines, monopolar spindles
can arise from the combined inhibition of Eg5 and Aurora A Kinase
(AURKA).8 Furthermore, phosphorylation of Kif15 by AURKA is re-
quired to target Kif15 to the spindle.23 While biochemical analysis re-
vealed that GW108X inhibits AURKA 67% at 1 µM, it is unknown if
GW108X effectively inhibits AURKA in cells.13
Concentration response analysis for GW108X and 2 was performed
using the ATPase assay, generating IC50 values of 0.82 µM for GW108X
and 2.5 µM for 2 (Figs. 1B (blue curve) and S2B). We decided to pursue
GW108X for further analysis because of its sub-micromolar IC50. To
further characterize the ability of GW108X to inhibit Kif15, we used the
MT-gliding assay. For this, we used Kif15-N700, a longer construct that
robustly glides MTs (see Materials and Methods).17 The inhibitory ac-
tivity of GW108X against Kif15 was scored by calculating the velocity
of MT gliding over a range of inhibitor concentrations to generate a
concentration response curve. The IC50 was 734 nM, similar to that
calculated using the ATPase assay (Fig. 1B (green curve) and C).
We next used the MT gliding assay to test whether the inhibition of
Kif15 by GW108X is reversible. We initiated MT gliding by Kif15 in the
presence of DMSO, and then introduced 10 µM of GW108X. Treatment
for 1 min was sufficient to eliminate MT gliding. GW108X was then
washed out, and the chamber was imaged for another minute. After
wash out of GW108X, MTs resumed gliding again, revealing that
GW108X inhibits Kif15 in a reversible manner (Fig. 1D, Supporting
Video 2). MT gliding was unaffected when only DMSO was washed in
(Fig. S2C). We then tested the ability of GW108X to inhibit Eg5, HSET,
and Kif18A, three additional mitotic motors that differ in both structure
and function.18–20 Despite promiscuity as a kinase inhibitor, GW108X
displayed a preference for Kif15 over the other mitotic motors, with
To probe the relationship between structure and Kif15 inhibition
activity of GW108X, we created a small library of derivatives with
modifications to both the furan and the phenol. The compounds were
prepared according to Scheme 1 (Fig. 2). We first explored conservative
changes around the hit compound. The requisite intermediate II was
synthesized from a Friedel-Crafts reaction from oxindole I. Condensa-
tion with various aromatic aldehydes gave the GW108X-inspired ana-
logs III. We also contemplated changes to the oxindole 5-position
substituent. Analogs V, with a furan or other aromatic ring directly
attached to the oxindole, were generated using palladium-mediated
Suzuki coupling reactions from readily accessible bromides IV. Simi-
larly, acids VI could be derivatized to corresponding amides VIII using
HATU-based amide coupling conditions.
To compare the activity of the GW108X derivatives, we tested their
ability to inhibit Kif15 MT-gliding at 750 nM, roughly the IC50 of
GW108X (Fig. 3). GW108X contains halogens in the ortho positions of
the phenol, which may provide opportunities for the formation of both
30 µM of GW108X inhibiting Kif15 MT gliding by 98.9%
only inhibiting Eg5 by 19.8% 4.3%, HSET by 5.3%
Kif18A by 4.9% 3.9 (mean
0.2% while
2.9% and
SEM, Fig. 1E). Taken together, these
assays show that GW108X has the ability to reversibly inhibit Kif15 and
suggests that the compound may exploit a Kif15-specific binding site for
inhibition.
To determine if GW108X affects Kif15 activity in cells, we first
analyzed its effects on Kif15 localization and activity in TP53−/− RPE-1
cells.21 In RPE-1 cells treated with 25 µM GW108X, 84% of pre-ana-
phase microtubule arrays were bipolar (n = 470), similar to cells
treated with DMSO (90% bipolar, n = 490), which is consistent with
previous work showing that Kif15 is not normally required for spindle
assembly (Fig. 1G).11,22 However, 25 μM of GW108X led to a 3-fold
decrease of spindle-bound Kif15 levels compared to DMSO, as assessed
by quantitative immunofluorescence microscopy (Fig. 1F and H). De-
crease in Kif15 levels on the spindle corresponds to a ∼60% decrease in
Kif15 protein levels in RPE-1 cells treated with 25 µM GW108X, sug-
gesting that GW108X treatment of cells leads to Kif15 degradation (Fig.
S3A and B). Despite a decrease of Kif15 in RPE-1 cells treated with
25 µM GW108X, spindle lengths were unaffected (Fig. S3C).
Fig. 2. Scheme 1. Reagents and conditions: a. AlCl3, DCE. 0 °C, 65% b. RCHO,
piperidine, EtOH, 80 °C, 40–70% c. ArB(OH)2, Pd(PH3)4, Na2CO3, 2:1 dioxane/
water, 110 °C, 20–79% d. amine, HATU, DIPEA, DMF, 57–64%.
To determine if GW108X inhibits the spindle assembly function of
Kif15, we tested whether GW108X blocks spindle assembly in an RPE-1
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Fig. 3. Structure-activity relationship (SAR) analysis of GW108X derivatives. Representative compounds from SAR library of phenol derivatives tested at 750 nM.
Data is the average microtubule gliding velocity of Kif15-N700 with each compound. Every compound was tested in triplicate with n ≥ 30 measurements for each
replicate, except 8 and 5, which were performed in duplicate. Error bars show SEM. See Table S1 for complete list of SAR compounds.
hydrogen and halogen bonds with biomolecules. Compounds 3 and 4,
with different halogens in the meta position, displayed, together with
GW108X, a structure activity relationship (SAR) that correlated with
halogen size. The Kif15 inhibition activity of the compound improved
as the halogen size increased from fluorine to bromine, with 4 in-
hibiting MT gliding by 65%. Interestingly, compounds that contain two
different halogens (6 and 7) showed intermediary inhibition also in line
with respective halogen size. The larger iodines of 5, however, were not
as well tolerated, and none of the compounds showed percent inhibi-
tion significantly different than that of GW108X. Unfortunately, more
aggressive changes in the aromatic ring substitutions served only to
demonstrate the importance of the hydroxyl and halogens for robust
inhibition of Kif15 (see also Table S1 for additional SAR). For example,
removal (8) or substitution (10, Table S1) of the phenolic hydroxyl
abolished activity. Furthermore, both halogen substituents appear to be
required, as compounds with the halogens replaced with methyl groups
(9) were reduced in activity. We found that the 5-position of the oxi-
ndole core was intolerant of changes, as these compounds did not ro-
bustly inhibit Kif15 MT-gliding (Table S1).
found that this concentration abolishes Kif15-driven MT gliding (Fig.
S4A). Concentration response analysis using the MT gliding assay re-
vealed that the IC50 was 203 nM, significantly lower than the previous
study (Fig. 4B).24 Similar to GW108X, Kif15-IN-1 was reversible in the
MT gliding assay (Fig. 4C, Supporting Video 3).
We next tested the effect of Kif15-IN-1 on Kif15 localization in RPE-
1 cells by treating them with 25 µM Kif15-IN-1. Unlike GW108X, Kif15-
IN-1 did not reduce spindle-bound levels of Kif15 and only decreased
Kif15 protein in whole cell lysates by 15% (Fig. 4D, E, and S4B and C).
Nevertheless, spindles were shorter in RPE-1 cells treated with 25 µM
Kif15-IN-1
(11.4 µm
(9.9 µm
0.3 µm)
compared
to
DMSO
0.2 µm), a phenotype consistent with knock-down of Kif15
(Fig. S4D).11,22, 25 Similar to GW108X, 25 µM Kif15-IN-1 had no effect
on spindle bipolarity of RPE-1 cells (96% of bipolar (n = 196) in Kif15-
IN-1-treated cells, 94% bipolar in DMSO-treated cells (n = 303)). In
KIRC-1 cells treated with 25 µM Kif15-IN-1, the percentage of mono-
polar pre-anaphase microtubule arrays increased from 43% in DMSO
(n = 260) to 84% (n = 269, Fig. 4F), similar to the increase observed
with GW108X.
A recently described inhibitor, Kif15-IN-1, was shown to inhibit
Kif15 as well as synergize with Eg5 inhibitors in both MT gliding and
cell viability assays.24 Kif15-IN-1 is a quinazolinedione, reported to
have an IC50 of 1.72 µM in the gliding assay (Fig. 4A). Since Kif15-IN-1
recently became commercially available, we compared its activity to
that of GW108X and characterized its effect on Kif15 in cells. First, we
repeated MT gliding assays using the reported IC50 of 1.72 µM and
In principle, GW108X and Kif15-IN-1 could inhibit the MT-stimu-
lated ATPase and MT gliding activity of Kif15 either by inhibiting ATP
binding or by inhibiting MT binding by the motor. To distinguish be-
tween these possibilities, we first measured the MT-stimulated ATPase
activity of Kif15-N700 at varying concentrations of ATP or MTs in the
presence of GW108X. When varying the concentration of a substrate, a
competitive inhibitor will change the KM while Vmax remains
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Fig. 4. Kif15-IN-1 is a sub-micromolar inhibitor of
Kif15. (A) Structure of Kif15-IN-1. (B) Concentration
response curve using the MT-gliding assay, devel-
oped from 5 concentrations of Kif15-IN-1, ranging
from 30 to 0.1 µM. Error bars show SD. (C)
Representative montage of fluorescent MTs from the
double wash out experiment. Each vertical frame
represents 10 s. Scale bar, 5 µm. (D) Representative
single optical sections of RPE-1 cells treated with
DMSO or 25 µM Kif15-IN-1 for 24 h and stained for
antibodies targeting Kif15 (grayscale and red), tu-
bulin (green) and DNA (blue). LUTs for grayscale,
red and green channels are scaled identically. Scale
bar, 5 µM. (E) Quantitation of RPE-1 cells treated
with DMSO or 25 µM Kif15-IN-1 for 24 h. Shown are
ratios of Kif15 fluorescence intensities to tubulin
intensities. Box-and-whisker plots describe the
median value as well as the 10th, 25th, 75th and
90th percentiles. n = 30 cells from triplicate ex-
periments. (F) Quantitation of the % pre-anaphase
structures in RPE-1 cells treated with DMSO or
25 µM Kif15-IN-1 for 24 h. Each condition was
tested in triplicate and graph displays average per-
cent from each triplicate. Errors bars show SD.
unchanged, whereas a non-competitive inhibitor will change the Vmax
with no change in the KM. When varying ATP concentrations in the
within the motor and instead each offer novel chemical space for Kif15
inhibition.
presence of GW108X at a high MT concentration, there was no change
This distinction in biochemical mechanism is important for two
reasons. If Kif15 contains two proximal inhibitor binding sites, it may
be possible to link compounds that target the two sites, creating a larger
molecule with the potential to occupy both sites. Conjugation of two
chemotypes might improve specificity and affinity of the inhibitor.
Secondly, dual-targeting of Kif15 with GW108X and Kif15-IN-1 should
decrease the possibility that KIF15 mutations could bypass drug me-
chanism.26
ATP
in the measured KM
and a decrease in the Vmax, indicating that
GW108X is not competing with ATP binding (Fig. 5A). In contrast,
when the MT concentration was varied in the presence of saturating
MT
ATP, an increase in the KM was observed, suggesting that GW108X
interferes with Kif15’s MT binding ability (Fig. 5B). This result is con-
sistent with the observed decrease of Kif15 on the spindle (Fig. 1H).
In contrast to GW108X, an increase in KMATP was observed when the
ATP concentration was varied in the presence of Kif15-IN-1, indicating
that instead of competing with MT binding, Kif15-IN-1 competes with
ATP binding (Fig. 5C). Since GW108X and Kif15-IN-1 display different
modes of inhibition, it is unlikely that they share the same binding site
Mitotic kinesin inhibitors are routinely used in cell biology labora-
tories and allow researchers to specifically modulate a motors activity
to give a predicted perturbation of MT or spindle dynamics. For ex-
ample, both ATP competitive and allosteric inhibitors of the mitotic
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Fig. 5. Kif15-IN-1 is a competitive ATP inhibitor and
GW108X is a non-competitive ATP inhibitor. (A)
Double reciprocal Lineweaver-Burk plot of ATP ti-
tration at 0.5, 1 and 2 µM GW108X. (B) Double re-
ciprocal Lineweaver-Burk plot of MT titration at 0.5
and 2 µM GW108X. (C) Double reciprocal
Lineweaver-Burk plot of ATP titration using 5 µM
Kif15-IN-1. Each reaction in A–C was performed in
triplicate. All error bars show SEM.
motors Eg5 and CENP-E have been extensively characterized both in
vitro and in clinical trials.27–29 Most recently, functionally distinct K5Is
were shown to have differential effects on both MT dynamics in vitro
and spindle stability in RPE-1 cells.30 While the canonical non-compe-
titive loop-5 targeting K5Is result in the classic monopolar spindle
phenotype, the ATP competitive inhibitor BRD9876 stabilizes MTs in
vitro and does not cause spindle collapse. Small molecule inhibitors that
can modulate Kif15’s mechanochemical cycle in different ways will also
be powerful tools for mitosis research. In the case of Kif15, its mitotic
function under normal conditions is not well understood. Kif15 loca-
lizes to kinetochore-MTs, regulating the stability and length of these
bundles.11 When over-expressed, as in K5I-resistant cells, Kif15 re-
localizes to non-KMTs and provides outward forces required for cen-
trosome separation. Small molecules that can acutely inhibit Kif15 in
these different cellular contexts through different mechanisms are likely
to reveal new properties and functions of Kif15 during mitosis.
for providing the kinase inhibitor library PKIS, https://www.sgc-unc.
org/kinase-chemogenomics/.
Appendix A. Supplementary data
Supplementary data to this article can be found online at https://
doi.org/10.1016/j.bmcl.2018.12.008.
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