MAPT and Alzheimer disease: Studies showed that the activated form of GSK‐3 was elevated in the AD brains.25 GSK‐3 could not only phosphorylate tau at most of the AD sites 26, 27, 28 but also induce Aβ overproduction.29 Activation or overexpression of GSK‐3 induces memory deficit,30, 31, 32 whereas inhibition of GSK‐3 reverses this effect.31, 33 However, the mechanism by which GSK‐3 regulates learning and memory is only partly understood.