Moreover, MDA-MB-231 cells that showed downregulated NOXA expression in response to doxorubicin underwent minimal apoptosis (Fig. 5B), and were also positive for SA-β-gal upregulation (Fig. 5C), consistent with previous observations that breast tumor cells exhibit a senescent profile in response to chemotherapy33, and show reduced NOXA expression28. Here, PMAIP1 is linked to breast neoplasm.