MUC1 and neoplasm: MUC1’s regulatory effect on the immune environment includes inhibiting myeloid-derived suppressor cells (MDSCs) proliferation and immunosuppressive functions, where its absence in mice leads to increased MDSCs numbers and activity, promoting tumor growth, and MUC1 deletion also heightens MDSCs’ release of factors such as iNOS, ARG1, and TGF-β, further inhibiting T cell activity (76).