OGA and Cerebral ischemia: Cellular death caused by sustained apoptosis and necrosis at the longer time points might also contribute to the reduction of protein O-GlcNAcylation, as the levels of OGT and OGA, especially of the latter, as well as of some other proteins (data not shown), were found to be decreased in a time-dependent manner, suggesting overall increase of protein degradation at the second phase of cerebral ischemia.