WNK2 and Alzheimer disease: The mitogen-activated protein kinase (MAPK) signaling pathway is engaged in the transcriptional regulation of neuronal apoptosis and has been shown to play a key role in AD [33], therefore the phosphorylation of extracellular signal-regulated protein kinases 1 and 2 (ERK1/2), a member of MAPK family, was also detected in the present study.