MDK and pulmonary arterial hypertension: Using IPA analysis, we characterized several over-expressed genes in PAH, in particular related to cardiovascular diseases, including the genes coding for caveolin-2 (CAV2), the vasoconstrictor angiotensin-converting enzyme gene (ACE), as well as molecules involved in angiogenesis and adhesion, such as midkine (MDK), and lectin galactoside-binding soluble 3 (LGALS3) (Figure 5B).