Expression analysis of PAAD tissues and normal tissues based on the TCGA database also indicated higher levels of TOP2A (Jiao et al., 2019), CDK1 (Jing et al., 2019), RRM2 (Zhao et al., 2019), PRC1 (Mao et al., 2019), NEK2 (Deng et al., 2019), ZWINT (Obuse et al., 2004), DTL(Cui et al., 2019), MELK (Meel et al., 2019), CENPF (Chen et al., 2019), CEP55 (Hauptman et al., 2019), ANLN (Wang et al., 2019), ASPM (Hsu et al., 2019), and ECT2 (Daulat et al., 2019) in tumor tissues. The gene discussed is RRM2; the disease is pancreatic adenocarcinoma.