ECM1 and breast cancer: To reason molecular mechanisms(s) by which ECM1 is required for the growth of endocrine-resistant ER+ breast cancer cells, we interrogated Cancer Dependency Map (DepMap) database (Ghandi et al. 2019), and then found that the level of ECM1 mRNA is positively correlated with that of Src phosphorylation at the tyrosine 416 (Y416) residue in ER+ breast cancer cell lines, but not in ER- breast cancer cell lines (Figure 4(C)).