CD184, also known as CXCR4, is a G protein-coupled receptor with seven transmembrane domains that serves as the receptor for stromal cell-derived factor-1 (SDF-1, also known as CXCL12). It is widely expressed in various tissues, including peripheral blood leukocytes, spleen, thymus, bone marrow, heart, placenta, lung, liver, skeletal muscle, kidney, pancreas, cerebellum, and endothelial cells. CXCR4 plays crucial roles in multiple physiological processes, such as cell migration, hematopoiesis, vascularization, neural development, and wound healing. It also acts as a co-receptor for T-cell tropic strains of HIV-1, facilitating viral entry into CD4+ cells. In cancer, CXCR4 is overexpressed in many tumor types and is associated with increased invasiveness, metastasis, and poor prognosis. Additionally, CXCR4 is involved in the homing of hematopoietic stem cells to the bone marrow and the retention of aged neutrophils.