CXCR4 and cancer: It is important to stress that besides CXCL12/CXCR4, our study disclosed further potential targets for breast CSC-directed therapy, such as Jag1, Postn, Tnc, and Il33. These factors have previously been shown to play a role in the regulation of cancer stemness16,29,30,46 and our results show that these potential BC niche-determining factors are expressed in human breast CAFs.