(A) CAT activity competition assay of double stranded oligomers containing wild-type (WT) or mutated (mut) Myb orEts-2 binding motifs in the transient transfections experiments in TK^-ts13 fibroblasts. pCAT B XhoI-BamHI (lane 1), pCAT B XhoI-BamHI + pCMV-myb (lane 2), pCAT B XhoI-BamHI + pCMV-myb + mut oligomers (lane 3), pCAT B XhoI-BamHI + pCMV-myb + wt oligomers (lane 4), pCAT BXhoI-BamHI + pCMV-ets-2 (lane 5), pCAT BXhoI-BamHI + pCMV-ets-2 + mut oligomers (lane 6), pCAT B XhoI-BamHI + pCMV-ets-2 + wt oligomers (lane 2; lane 7), pCAT B XhoI-BamHI + pCDN3 (lane 9). (B) Densitometric quantitation of CAT activity in transiently, MYB and Ets-2 expressing TK^-ts 13 cells cotransfected with a pCAT B plasmids containing theXhoI-BamHI c-kit 5′ flanking region and 200 molar excess of wt or mut oligomers. CAT activity present in cells transfected with the pCAT B XhoI-BamHI + pCMV-myb constructs was arbitrarily given a value of 100%. Mean ±SD of six different experiments, each performed in duplicate, are shown.