Next, we knocked down AMPK gene by transient transfection of specific siRNA, inhibition of AMPK by siRNA ablated the effects of CTRP9 on the eNOS (Figure 4C,D), NO production (Figure 4E), and endothelial dysfunction (Figure S4) in ox-LDL-stimulated HUVECs. The gene discussed is PRKAA1; the disease is endothelial dysfunction.