KLK4 and pulmonary arterial hypertension: Our proteome data illustrated that plasma kallikrein (complement and coagulation cascades Pathway), complement component C9 and ranoclass II (both in systemic lupus erythematosus pathway), CD63 antigen, legumain, Cathepsin S, Cathepsin Z, lysosomal acid lipase(proteins in lysosome pathway) were highly enhanced in PAH, Whereas Histone H3.3, Histone H 3.1(proteins in systemic lupus erythematosus pathway), HMGB1 (base excision repair pathway) were considerably down-regulated in PAH progression, these proteins were markedly recovered by osthole treatment.