The key genes identified for basal-like breast cancer were CENPI, CENPK, CDC7, CCNE2, KIF18A, STIL, CDCA7, and CKS2. The small cell lung cancer pathway was enriched for CCNE2 and CKS2, and the cell cycle pathway was enriched for CDC7 and CCNE2 (P < 0.05). This evidence concerns the gene CCNE2 and small cell lung carcinoma.