C-X-C motif chemokine receptor type 4 (CXCR4)

CXCR4 (C-X-C chemokine receptor type 4) is a G protein-coupled receptor (GPCR) primarily expressed on white blood cells and in the central nervous system. Its main ligand is SDF-1/CXCL12. Activation of CXCR4 triggers signaling pathways that regulate cell migration, proliferation, and survival. It plays roles in hematopoiesis, immune responses, neuronal development, and has been implicated in cancer metastasis and HIV infection. Unlike many chemokine receptors, CXCR4 exhibits high specificity for SDF-1.

CXCR4 antagonists block the interaction of CXCR4 with its ligands (primarily CXCL12/SDF-1), thereby inhibiting downstream signaling pathways involved in cell migration, proliferation, and survival. This can sensitize tumors to chemotherapy agents or disrupt viral entry into cells.