FIG. 4.
Induction of E2F-1 in response to UVC irradiation is mediated by prolongation of the half-life of E2F. (A) U2-OS cells irradiated with UVC (30 J/m2) or an unirradiated control was further incubated for 16 h before addition of 20 μg of cycloheximide (CHX) per ml. After a further incubation for the indicated periods, the cells were harvested and 45 μg (control) or 20 μg (UVC irradiated) of cellular protein was resolved on a 10% polyacrylamide minigel. The blots were probed for E2F-1 expression by using the rabbit polyclonal anti-E2F-1 antibody C-20. The blots were reprobed with an anti-PCNA antibody (PC10) to show loading of the samples. (B) E2F-1 expression was quantified, and the mean value of E2F-1 expression of two independent experiments was plotted.