SLC9A1 and cancer: Although NHE1 is highly expressed in several cancer cell lines (49) and is the most widely studied isoform, gene expression analyses indicate that NHE6, 7, and 8 are expressed at levels comparable to NHE1 in PDAC cells (50); therefore, it would be useful to conduct further studies aimed at identifying the contribution of specific NHE isoforms to macropinocytosis.