Figure 8.

A schematic model for p38 MAPK-mediated MafA degradation under oxidative and nonoxidative conditions. Red circles represent GSK3 phosphorylation sites, yellow circles represent common T57 phosphorylation site for p38 MAPK and GSK3, green circles represent T134 phosphorylation site, and P denotes phosphorylation. The absence of phosphorylation at the A134 site is shown by an empty circle. Potential pathways for degradation of WT-MafA and A134-MafA under oxidative and nonoxidative conditions are shown. Circles with U indicate ubiquitination; intact and degraded MafA are shown by single ovals and 2 structures, respectively. Reduced expression of PA28γ under oxidative stress is shown by downward arrow and red font; higher expression levels are indicted by bold green font for PA28γ, and dark green arrow shows increased p38 MAPK expression under oxidative stress. Darker green arrow indicates dominant MafA degradation pathway under oxidative stress.