Within the important genes, gene frequency was further calculated, and genes co-occurred in more than ten cancer types were identified as hot cancer genes, which included MYC, AKT1, BCL2, MCL1, CASP8, BAX, MAPK8, CDKN1A, PCNA, MTOR, PTEN, BCL2L11, VEGFA, FASN, PARP1, PIK3R1, EGFR, CDK2, JUN, CASP3, BCL2L1, FLT4, XIAP, BAD, PRKAA1, PRKAB1, CDK1, STAT3, BECN1, and MAP1LC3B. The gene discussed is PCNA; the disease is cancer.