RB1 and neoplasm: Rb-deficient tumor cells also displayed increased susceptibility to BETi-mediated reprogramming of their immune phenotype, including decreased expression of checkpoint ligands such as PD-L1, Gal9, and VISTA, decreased expression of chemokines associated with tumor growth and immune suppression such as CXCL1 and CXCL5, as well as a complete restoration of T cell migration.