CXCR2 and pulmonary arterial hypertension: Proteomic analysis also revealed reduced RAC2 (Ras-related Rho GTPase) (P = 0.03; FDR, 9%) and C-X-C motif chemokine receptor 2 (CXCR2) (P = 0.04; FDR, 11%; Figure 3C) in PAH versus control samples.