CXCR6 and breast cancer: Research has demonstrated that the protein GTPase activator regulator of G protein 1 (RGS1) in tumor-specific circulating T cells acts as a suppressor of chemokine G protein-coupled receptors (GPCRs) signaling, leading to reduced T cell motility and decreased levels of infiltration by CTL and Th1 cells in mouse models, breast cancer, and lung cancer patients,66 underscoring the significance of regulating chemokine receptor function.