E2F1 and central nervous system cancer: We also knocked down E2F1 in other cancer cell lines (human hepatocellular carcinoma, QGY-7701; human glioma, U343; human non-small-cell lung carcinoma, A549; human pancreatic carcinoma, AsPC-1; human cervical carcinoma, HeLa) in which E2F1 and CKS2 were both highly expressed based on TCGA database (Supplemental Figs. S7 and S8) and exhibited positive co-expression between E2F1 and CKS2 (Fig. 3B, C).