CDK4 and neoplasm: To confirm the PRKDC-CDK4 cascade in promoting tumor cell proliferation, we collected PDCs from patients for further analysis (PDC_PRKDCAmp&CDK4Amp: patients belonging to S-III and harboring both PRKDC amplification and CDK4 amplification; PDC_WT: patients without PRKDC amplification and CDK4 amplification).