c-MYC inhibition either by a small molecule inhibitor (10058-F4) or by RNA interference (RNAi) causes in vitro growth arrest and alters target gene expression. (A) c-Myc inhibitor (10058-F4) abrogated colony formation of LNCaP and DU145 cells in soft agar assay. # indicates no colonies. *P < 0.0001, **P < 0.002. (B) Control and Pim1-expressing LNCaP and DU145 cells were treated with different doses (0, 50, 100 and 200 uM) of 10058-F4. Note that 10058-F4 inhibits protein expression of Pim1, but not Pim1 mRNA. (C) Control and two small hairpin RNA constructs (sh1 and sh2) against c-MYC were transfected in LNCaP-Pim1 cells to knock down c-MYC expression. Relative c-MYC expression is shown. (D) Expression of some target genes (LAMC2 and VAV3) in LNCaP cells was reversed by repression of c-MYC levels in a dose-dependent manner. * indicates altered target gene expression by c-MYC knock-down.