FIGURE 5.

st induces CDC6 mRNA expression in a CDK-independent, E2F-dependent manner. A, BJ-hTERT cells stably expressing a dominant negative E2F/pRB mutant chimera or the empty expression vector (r-control) (see text) were serum-starved for 72 h immediately after antibiotic selection and re-stimulated with FBS or transduced with control or st adenovirus. Cells were harvested for RNA analysis 40 h later. B, radioactive signals were quantified, normalized by ribosomal RNA loading, and represented as fold increase in mRNA as in Fig. 4. C, BJ-hTERT cells were serum-starved for 48 h and transduced with adenovirus expressing p21 and/or p16. Twenty-four hours later, cells were re-stimulated with FBS or transduced with st adenovirus. Forty hours later, cells were harvested for Northern blot analysis. D, radioactive signal was quantified as in B.