CSF1 and neoplasm: M‐CSF is another substance secreted by tumor cells that inhibits the normal differentiation of B‐cells.[48] Tumor‐derived M‐CSF promotes the downregulation of Pax5 expression in CSF1R + immature B‐cells, which leads to macrophage‐like cell differentiation.[48] These macrophage‐like cells have a role in inhibiting effector T cell proliferation and promoting tumor infiltration.