NFKB1 and breast cancer: Long et al. (2012) reported that ovarian cancer stem cells promote tumor metastasis by expressing high levels of CCL5, activating the NF-κB signaling pathway in an autocrine manner and up-regulating the expression of MMP-9. Ginestier et al. (2010) reported that breast cancer stem cells highly expressed CXCR1 receptor, and that IL-8 (a ligand of CXCR1) was able to enhance the proportion of CSCs and maintain the stemness of CSCs.