HSPA5 and Parkinson disease: For example, Gorbatyuk and colleagues in a rat model of PD induced by an elevated level of human α-synuclein demonstrated that although the accumulation of α-synuclein induced the expression of apoptosis-regulating ATF4, the upregulation of GRP78/BiP inhibited α-synuclein toxicity by regulating ER stress signaling pathways [49].