CXCL12 and breast cancer: This effect was possibly due to the capability of CXCL12 to block infiltration of CXCR4‐expressing T cells.113 MRC5 fibroblasts, foreskin fibroblasts, and mammary CAFs co‐cultured with MDA‐MB‐231, Hs578T, MDA‐MB‐436, MDA‐MB‐157, or HCC1937 basal‐like ER− breast cancer cells induced interferon‐stimulated genes, which drove mechanisms of resistance to chemotherapy and radiation through the activation of STAT1 in the cancer cells.