ESR1 and breast carcinoma: We then verified the acidification ability of breast and renal carcinoma cells by directly measuring their proton production rate, and we found a significant extracellular secretion of protons as a consequence of both glycolytic-dependent and -independent mechanisms for all the tested carcinoma cell lines, but the less aggressive estrogen receptor-positive MCF7 breast carcinoma cells (Kirschmann et al., 1999; Wright et al., 2016).