WNK2 and hepatocellular carcinoma: The entry of Ca2+ into hepatocellular carcinoma cells, caused by the piezoelectric ceramic-specific activator Yoda1, activates the phosphorylation of Jun N-terminal kinases (JNK), mitogen-activated protein kinase (p38) and extracellular regulated protein kinases (ERKs) and activates the mitogen-activated protein kinase (MAPK) pathway in a time- and dose-dependent manner.