We found that silencing CDC7 caused apoptosis in A549 (Figures 3e and a, lower panel), as CIS did so (Figures 3a–c), whereas CDC7 overexpression diminished CIS-induced apoptosis (Figures 3h and i and Supplementary Figure S5), indicating that CDC7 downregulation is responsible at least partly for CIS-induced apoptosis. Here, CDC7 is linked to in situ carcinoma.