ATF6 and urea cycle disorder: These findings suggest that the ER is under stress, as evidenced by the upregulation of two key ER stress markers, ATF6 and phosphorylated eIF2α All of the foregoing assessments of splenic lymphocytes obtained from diabetic UCD-T2DM rats display characteristics of immune cells with impaired signaling functions and deteriorating ER functional integrity, which are likely to manifest in deficiencies in immune function.