An rBCG strain that produces a hybrid protein composed of repeated MUC1 epitopes fused to GM-CSF (rBCG::MUC1-GM-CSF) was found to significantly limit tumor growth and prolong the survival of mice inoculated with MUC1+ breast cancer cells, while a pBCG or rBCG::MUC1-GM-CSF strain containing a single repeat of the epitope did not [67], indicating the predominant role of the MUC1 epitope over GM-CSF in tumor growth inhibition and mouse survival. This evidence concerns the gene CSF2 and breast carcinoma.