HIF-1α counteracts Myc activity. (A) Effect of ΔODD on Myc transcriptional activity was examined with an hTERT luciferase reporter in HCT116 cells. The graph represents three independent experiments in duplicate. (B) Myc target genes, as indicated, were analyzed by RT–PCR after adenoviral infection. c-myc mRNA levels were also determined. (C) After transfection with c-myc siRNA (siRNA), HCT116 cells were infected with Ad-ΔODD and analyzed with RT–PCR for Myc target gene expression, as indicated. CON, no siRNA. Neg, negative control siRNA.