CDK4 and cancer: Although existing studies have demonstrated that MZF1 binds to the activation site of cyclin-dependent kinase 4 (CDK4) and accelerates the ubiquitination of PD-L1, thereby promoting tumor progression in hepatocellular carcinoma and enhancing resistance to anti-PD-L1 antibodies, its precise mechanisms of action across various cancers remain to be further elucidated (60).