Gene expression of Cx37 (encoded by GJA4), Cx40 (encoded by GJA5), Cx45 (encoded by GJC1), and Panx1 was assessed in pulmonary arteries from Cx43+/− mice along with gene expression of various mediators known to play a role in the development of PAH: Tph1, endothelial nitric oxide synthase (eNOS, encoded by NOS3), and bone morphogenetic receptor type II (BMPRII, encoded by BMPR2). This evidence concerns the gene GJA4 and pulmonary arterial hypertension.