Being a key protein phosphatase in dephosphorylating tau, protein phosphatase-2A (PP2A) is compromised in the AD brains (Liu et al., 2005; Liang et al., 2008), while the level of its endogenous specific inhibitor 2 (I2PP2A), also known as SET, is increased (Tanimukai et al., 2005). The gene discussed is PTPA; the disease is Alzheimer disease.