Detection of CRT and MUC1 promoting a phagocytic signal on the cell surface of apoptotic 4T1 cells by DNA fragmentation analysis. DNA fragmentation was induced by mitoxantrone (10 µg/ml) for 24 h. Lane 1, 4T1 control cells; lane 2, 4T1 cells transiently transfected with pEGFP-MUC1; lane 3, 4T1 cells transiently transfected with pEGFP-CRT; lane 4, 4T1 cells transiently transfected with pEGFP-MUC1-CRT; M1 and M2, DNA markers. MUC1, mucin 1; CRT, calreticulin.