HSPA5 and Anxiety: In this regard, it is noteworthy that Atf6a−/− mice, in which the expression of GRP78 was reduced to approximately 50–75% of wild-type mice in the brain, developed almost normally in the physiological condition,10,32 while Atf6β−/− mice, in which the expression of CRT was specifically reduced to approximately 50% of the wild-type mice in the brain, elicited anxiety-like behavior and hyperactivity.15