MUC1 also binds to Siglec‐9 on the surface of bone marrow cells such as tumor‐associated macrophages (TAMs) and DCs, promotes the secretion of factors related to tumor progression, and activates the MEK–ERK signaling axis to regulate the phenotype of TAMs in the TME to promote tumor progression [20]. This evidence concerns the gene SIGLEC9 and neoplasm.