CD164 and breast cancer: 38 In recent years, many studies have indicated that CD164 played a role in tumor progression by interacting with CXCR4 and regulating the downstream of CXCR4 pathway.23 Knocking‐down of CD164 could up‐regulate PTEN and inhibit the activities of PI3K/AKT pathway.13 Besides, CD164 promoted lung tumor‐initiating cells with stem cell activity and determined tumor growth and drug resistance through Akt/mTOR signaling pathway.14 Therefore, we suspected that CD164 may also play roles in tumor progression of BC through CXCR4/AKT signaling pathway.