E2F1 and cancer: The increased proliferation rate of the three prostate cancer cells was paralleled by augmented protein levels of the pro-proliferative gene products E2F1, cyclin D1, cyclin E1 and cyclin A2, compared with the non-tumourigenic PZHPV-7 line (Figure 1D); increased expression of these genes typically associate with cancer transformation (Hwang and Clurman, 2005; Ladu et al, 2008; Li et al, 2010).