RB1 and metastatic prostate carcinoma: For example, a study discovered that cyclin-dependent kinase 4/6 (CDK4/6) phosphorylation of Rb at S249 and T252 enhances Rb interaction with p65, thereby inhibiting p65-dependent transcription of programed death-ligand 1 (PD-L1), among other genes, in metastatic prostate cancer [62].