SLC9C1 and cancer: Although this study only addressed NHE inhibition of EGF-induced macropinocytosis in A431 cells, it is likely that similar mechanisms account for amiloride/EIPA inhibition in the setting of other growth factors and in Ras-induced macropinocytosis, where H+ accumulation caused by increased metabolic activity and actin polymerization also occurs, especially in cancer cells where the high metabolic rate is well known to promote acidification of the cell and the tumor microenvironment (45–47).