Knockdown of CMTM4 in IL‐4‐treated M2 macrophages overwhelmingly inhibited their development, and in vitro co‐culture confirmed that tumor cell‐derived CMTM4 boosted M2 polarization, indicating that CMTM4 promotes macrophage‐mediated malignancy (Figure S6D‐G, Supporting Information). Here, IL4 is linked to neoplasm.