GAPDH and diabetes mellitus: As expected, diabetes reduced Ser1177 phosphorylation of eNOS by 57% (P = 0.0257; reported to GAPDH) and 70% (P = 0.0448; reported to total eNOS) (Figures 5A,F,G) compared to normoglycemic animals but had little impact on eNOS Ser633 activation.