E2F1 and cervical cancer: Because an oncogenic role of E2F1 and E2F8 in cervical cancer has been reported [24, 25], we knocked down E2F2 and E2F7 by shRNA in cells from the cervical cancer cell lines HeLa and C-33 A, and further investigated to assess the effect of E2F2 and E2F7 knockdown on cellular functions of HeLa and C-33 A cells.