In order to elucidate the mechanism of chemoresistance in triple-negative breast cancer, Lee et al. [36] reported that breast chemotherapy-resistant cancer stem cells rely on OXPHOS, and its activation is induced by increased MYC (a proto-oncogene that encodes a transcription factor) and MCL1 (an antiapoptotic Bcl-2 family protein) levels. Here, MCL1 is linked to triple-negative breast carcinoma.