ARG1 and type 2 diabetes mellitus: Interestingly, incubation of aortas from endothelial cell arginase-1–KO mice with T2D RBC-EVs led to increased expression of arginase-1 in the vessel wall, including endothelial cells (Figure 6, D and E), similar to what was observed in WT mouse aortas incubated with T2D RBC-EVs (Figure 5, A and B).