MAPT and Alzheimer disease: However, the neuroprotective effect of calycosin could be blocked by calphostin C, an inhibitor of protein kinase C, suggesting that calycosin ameliorated cognitive deficits in AD model mice through the protein kinase C pathway, including suppressing the production of proinflammatory cytokines, Aβ, tau, and ROS, as well as the activity of AchE.