CDK4 and neoplasm: On the other side, however, the senescent phenotype induced by CDK4 and CDK6 inhibition, results in the presence of metabolically active senescent cells that produce proinflammatory cytokines and promigratory factors, collectively termed the senescence-associated secretory phenotype (SASP).65 As a consequence, CDK4 and CDK6 inhibition might modulate the tumor microenvironment enhancing immune cell infiltration through SASP.