CXCR4 and neoplasm: Additionally, RGS1 inhibits the activation of calcium pathways downstream of GPCRs by binding to the chemokine receptors C-X-C chemokine receptor 3 (CXCR3), CXCR4, and C-C chemokine receptor 4 (CCR4), which, in turn, suppresses the ERK and AKT signaling pathways, ultimately hindering T-cell migration to tumor sites.