Earlier studies by some of us [25-27] demonstrated that MUC-1 glycoprotein, which is over-expressed and secreted by breast cancer cells, is endocytosed by DCs but is mostly retained in early endosomes; this leads to its inefficient processing and presentation to T cells, and hence a lower frequency of MUC-1 specific effector cells. The gene discussed is MUC1; the disease is breast carcinoma.