HMOX1 and endothelial dysfunction: It is noted that knockdown of PGC1-α or AMPK suppressed CTRP9-mediated antioxidant enzymes inductions including HO-1, NQO-1, GCLC, and GCLM, these results hinted that PGC1-α/AMPK-dependent antioxidant enzymes induction was responsible for the protective actions of CTRP9 in ox-LDL-mediated endothelial dysfunction.