MAPK3 and diabetes mellitus: Compared with the control group, the phosphorylation levels of SMAD2 and ERK1/2 were significantly enhanced in DM mice (p < 0.05, Fig. 5A–B), while the protein levels of TGF-β1, TGF-β receptor I (TGF-βR1), and the phosphorylation levels of PI3K and AKT had no significant changes (p > 0.05, Fig. 5A–B).