However, the observations obtained with regard to the increased sensitivity to RhoA in PAH cells go in hand with our mass spectrometry results showing that the expression of Rho GTPase-activating protein-1 is approximately 1.5 fold higher in PAH HPASMC relative to non-PAH HPASMC (unpublished data). This evidence concerns the gene ARHGAP1 and pulmonary arterial hypertension.