In a recent study by Ricard et al. [46], isolated endothelial ERK1 deficiency did not affect arteriogenesis, whereas global ERK1 deficiency or combined endothelial and macrophage ERK1 deficiency resulted in increased but dysfunctional arteriogenesis in a mouse model of acute hindlimb ischemia. The gene discussed is MAPK3; the disease is hyperinsulinemic hypoglycemia, familial, 4.