CXCL12 and breast cancer: Immunofluorescence and IHC have shown that CXCL12 is expressed most likely in the tumor cells and expression rates of 70.9% [44], 66.8% [31] or 70.6% [43] in breast tumors are relatively close to the CXCL12 expression obtained for feline mammary tumors in this study (78.1%).