Therefore, to elucidate the intracellular signaling pathway that mediates XCL1-induced breast cancer cell migration, the effects of the XCL1–XCR1 axis on EMT markers, ERK1/2 activation, and HIF-1α expression were also examined in MDA-MB-231 and SK-BR-3 cells in this study. The gene discussed is XCL1; the disease is breast carcinoma.