To further characterise the relationship between key effectors of G1/S transition and the regulation of human TS transcription, we infected HCT116 and MCF-7 cells with recombinant adenoviruses expressing E2F1, Dp1 and cyclin E. Western blot analysis revealed that, 24 h post-infection, both cyclin E and E2F1 were over-expressed in both cell lines (Figure 4A and C). This evidence concerns the gene E2F1 and infection.