FIG 6.

Effect of c-MYC depletion on E1A-Ras cooperative transformation. (A to C) HNK cells were infected with retroviral vectors that express the Δ178–238 E1A mutant and the activated H-Ras oncogene, along with lentiviral vectors that express specific shRNAs targeted against c-MYC (A), ENY2 (B), MAX (C), or GFP. The cells were then selected with puromycin. The foci were stained with crystal violet and counted (graphs). The transduction of retroviral vectors that expressed only E1A-12S-177-9 (Δ178–238) or H-Ras induced low numbers of lightly stained (with crystal violet) colonies that were readily distinguished and discarded during quantification. The activities of shRNA vectors in the downregulation of c-MYC (A), ENY2 (B), and MAX (C) were determined in HeLa cells with different lentiviral vectors and selection with puromycin (blots). (D) Western blot analysis of E1A and Ras proteins. Seventy-two hours after transduction with different retroviral vectors and shRNA lentiviral vectors, HNK cells were analyzed by Western blotting using the E1A Ab (M58) and Ras antibodies.