OGA and Alzheimer disease: However, a reduction in Tau phosphorylation in response to raising cellular O-GlcNAc levels has not been universally reported: while two studies observed reduced phosphorylation of Tau in response to OGA inhibition (TMG, MK-8719) in rTg4510 mice [166,170], phosphorylation was not markedly affected in the JNPL3 and Tau.P301L AD mouse models (TMG) [162,165].