MUC1 and breast carcinoma: Transgenic mouse models of breast cancer show that vaccination against multiple tumor antigens is superior to immunizing against a single protein.59 Vaccination against MUC1 and CEA results in generation of T-cell responses to a cascade antigen called brachyury.60 Brachyury is a transcription factor associated with tumor plasticity61 and is overexpressed in breast cancer, particularly TNBC.