MUC1 and breast carcinoma: In repeated coprecipitation experiments we confirmed this CIN85/MUC1 association in RMA-MUC1 by showing their coprecipitation from the MUC1-transfected mouse ovarian tumor cell line IG10-MUC1 and the human breast cancer cell line MDA-MB-231 that naturally overexpresses MUC1 (Fig. 1B).