Validation of antibodies. A, CHOP antibody staining in WT mouse ventral midbrain cultured cells that are also positive for TH (data not shown). Left, No drug. Right, Twenty hours in 3 μm Tu. The left and right graphs show the nuclear and cytoplasmic CHOP intensity, respectively. B, ATF6 antibody staining in slices from adult mouse substantia nigra. Double staining with anti-TH and anti-ATF6 shows that all DA neurons also stain for ATF6.