Liao et al. [60] screened out 5 highly expressed hub genes (NDC80, BUB1B, PLK1, CDC20, and MAD2L1) from 4 datasets (GSE60052, GSE43346, GSE15240, and GSE6044), and the cell cycle pathway was considered to be the main pathway for the diagnosis and treatment of SCLC of these five hub genes. Here, PLK1 is linked to small cell lung carcinoma.