CXCL12 and cancer: Exosomal CMTM4 activates the NF‐κB pathway in TAMs, suppressing immune function through enhanced secretion of cytokines, including TGF‐β1 and CXCL12, while simultaneously upregulating intercellular adhesion molecule‐1 (ICAM1) expression to further promote M2 polarization and facilitate cancer metastasis.