MAPT and type 2 diabetes mellitus: Moreover, Li et al. (71) reported recently that, despite the amelioration in c-Jun-N-terminal kinase activity (JNK, a kinase known to increase tau protein phosphorylation) and in hippocampal expression of the synaptic protein synaptophysin in the metformin-treated db/db mouse model of T2D, this was not accompanied by an amelioration of spatial learning and memory impairments.