MAPK3 and major depressive disorder: In terms of angiogenesis, vascular remodeling, and the BBB, the ALFF-related gene set was significantly enriched in the VEGF signaling pathway (P = 0.001), with the key regulatory gene MAPK3 (ERK1) (z-score = 12.568) closely linked to the pathogenesis, pathological features, and treatment response of depression through its signaling cascade (37, 38).