HDAC9 and Alzheimer disease: This pathway shows the upregulation of genes encoding for key proteins like glutamate receptor subunits (GRIN1, GRIN2c, and GRIA), CAMKII, HDAC, MEF2, Actin alfa, as well as NCX, the gene encoding for the Na+-Ca2+ exchanger, PMCA that encodes for the Na+-Ca2+/ATPase pump as well as nAchR that encodes for the nicotinic receptor, a key receptor involved in AD [15].