CXCL12 and breast cancer: This SNP involves a guanine to adenine (G → A) substitution at base pair 801 of the 3′-untranslated region of CXCL12 gene (Modi et al., 2005; Petersen et al., 2005) which is associated with BC progression in various studies (Chang et al., 2009; Chen et al., 2006; Hidalgo-Pascual et al., 2007; Maley et al., 2009).