RB1 and cervical squamous intraepithelial neoplasia: In addition to the investigation of mitotic genes, which were found to be rarely mutated [21, 50], genes in the other cell cycle phases, as for example RB1 [51], MYC [52], CCDN1 [53], and CCNE1 [54], have been investigated and proposed to lead to CIN by uncoupling cell cycle progression and mitotic control.