CACYBP and pulmonary arterial hypertension: On the basis of our findings that (1) CacyBP/SIP levels decreased in the pulmonary arterioles of patients with CHD-PAH and in flow-associated PAH rats, and (2) low CacyBP/SIP expression induced the phenotypic switch and excessive proliferation and migration of hPASMCs, we hypothesized that decreased CacyBP/SIP expression may promote vascular remodeling in PAH.