MUC1 and cancer: An MTT assay performed on mouse colon carcinoma cells and on Chinese hamster ovary cells (MUC1 positive and MUC1 negative, respectively), evidenced that the targeted vesicles resulted more cytotoxic on the cancer cells, while no significant difference was found in targeted and untargeted vesicle cytotoxicity on the healthy cells; in all cases, free CPT cytotoxicity was higher than that of the vesicle, as the free molecule can probably enter the cells via diffusion rather than endocytosis.