Furthermore, the most significantly down-regulated miRNAs, miR-26b, was selected for further functional analysis due to its well documented role in regulating human cell proliferation [30, 31], as well as the predicted function to suppress the expression of CTGF and CCND1(www.targetscan.org), upregulation of which have both been reported to contribute to the development of PAH in our previous studies [29, 32, 33]. Here, CCN2 is linked to pulmonary arterial hypertension.