ARF6 and pulmonary arterial hypertension: To assess the functional role of CLIC4/Arf6 in experimental models of PAH, we used DACC siRNA delivery system to target CLIC4siRNA to the lung endothelium.18 The analysis of the tissue distribution of siRNA-Cy3-labeled DACC formulation confirmed that DACC directs the siRNA predominantly to the lung endothelium (Figure 4D; Online Figure XIII), consistent with previously published data.18 Treatment with DACC/CLIC4siRNA formulation significantly reduced CLIC4 mRNA and protein levels in the lungs of these animals (Online Figure XIV).