Although activation of YAP was identified to repress ERα transcription and inhibit cell growth in ER+ breast tumor cells, a recent study reported that YAP was elevated in tamoxifen‐resistant breast cancer, and overexpression of YAP led to downregulation of ERα expression and conferred resistance to antihormone therapy in ER+ breast cancer.[23] Therefore, the role of YAP in ER+ breast cancer, and the contribution of YAP in obese‐related ER+ breast tumor progression is warranted to investigate. This evidence concerns the gene ESR1 and breast cancer.