ASIC2 and neoplasm: Tumor cells adapt to low environmental pH by activating pH sensors such as proton-sensitive cation channels of the degenerin/epithelial sodium channel (DEG/ENaC) family, which are trimers consisting of homologous subunits ASIC1a, ASIC1b, ASIC2a, ASIC2b, ASIC3, ASIC4, and α–δ ENaC [9,10,11,12,13].