ESR1 and breast cancer: MCF7 is a caspase-3 deficient breast cancer cell line (Supplementary Figure S1B), and targeting survivin by the small molecule inhibitor YM155 has been shown to induce caspase-independent, but autophagy-dependent, DNA damage and cell death in breast cancer cells regardless of the status of caspase-3, p53, and ER (Cheng et al., 2015).