CDK4 and cancer: To understand whether CDK4/6i‐induced senescent cells—which express a PASP but lacks the NASP—influence cancer cell proliferation, we measured the growth of MCF7 (breast cancer) (Fig 5A), and A549 and HCC827 (lung cancer) (Fig EV5A) cells exposed to the conditioned media (CM) of doxorubicin‐induced or abemaciclib‐induced senescent cells.