Other reported PrPc signaling pathways that are important in the regulation of chemical neurotransmission include phosphoinositide 3 kinase (PI3K), Akt protein kinase A (PKA), MAP kinase ERK1/2, mammalian target of rapamycin (mTOR) and calcium signaling—molecular mechanisms underlying the pathophysiology and treatment of mood disorders [23,24,25]. Here, PRNP is linked to mood disorder.