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Ack n ow led gm en t. We wish to acknowledge the
technical assistance of Patrick M. Callaghan who pre-
pared liver microsomes from rats and carried out the
initial assays of MROD activity in the IS-treated rats.
This research was supported in part by NIH Grants
CA38192 (W.L.A.) and CA44353 and ES00267 (F.P.G.).
L.C.B. is a predoctoral trainee supported in part by
ES07028.
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