CXCL12 and cancer: A particularly important role in chemotaxis is played by the chemokine receptor, CXCR4, and by its ligand, CXCL12 (also known as SDF1, stromal cell-derived factor (1), which initiate directed cell migration in various kinds of cancer (Archibald et al., 2012; Hu et al., 2014; Li et al., 2014; Yang et al., 2015).