CCND1 and pulmonary arterial hypertension: Resveratrol preserved the expression of SIRT1 and p21 and prevented the increase of cyclin D1 expression in the lungs of MCT-induced PAH rats. In vitro and in vivo experiments suggested that SIRT1-mediated regulation of p21 and cyclin D1 expression contributed to the antipulmonary arterial remodeling effect of resveratrol.