When we further applied a bioinformatics analysis using UALCAN and GEPIA2, we identified increased mRNA expression levels of CCND1/CDK4/PLK1/CD44 in multiple cancer types, which resulted in shorter overall survival times and poor prognoses in cancer patients, with p-values less than 0.05 and hazard ratios more than 1 considered to be significant (Figure 2 and Figure 3). The gene discussed is PLK1; the disease is cancer.