(complementary DNA). A piece of DNA copied from an mRNA. The term “clone” indicates that this cDNA has been spliced into a plasmid or other vector in order to propagate it. A cDNA clone may contain DNA copies of such typical mRNA regions as coding sequence, 5′-untranslated region, 3′ untranslated region or poly(A) tail. No introns will be present, nor any promoter sequences (or other 5′ or 3′ flanking regions). A “full-length” cDNA clone is one which contains all of the mRNA sequence from nucleotide #1 through to the poly(A) tail.