SRC and pulmonary arterial hypertension: c-Src may be involved in transactivation and phosphorylation of subunits required for Nox assembly21 and is a proximal regulator of vascular Nox activation.16 Exposure of PAH-hPASMCs to a Src kinase inhibitor, PP2, inhibited serotonin-induced ROS in PAH-hPASMCs while having no effect in control hPASMCs (Figure 2A).