DPP9 and endothelial dysfunction: FAP inhibition might reduce plaque instability by decreasing collagen breakdown; DPP9 inhibition is likely to attenuate M1 macrophage activation, reducing the local inflammatory cascade; DPPIV inhibition may decrease monocyte infiltration, foam cell formation, improve endothelial dysfunction, and reduce smooth muscle cell proliferation; and finally, PREP inhibition might reduce neutrophil infiltration, preventing endothelial dysfunction, and monocyte infiltration.