Distinctive traits of normal and tumor-derived human mammary epithelial cells expressed in a medium that supports long-term growth of both cell types.

A medium is described that supports long-term growth in culture of human primary mammary tumor cells, of normal epithelial cells from mammoplasty, and of mammary tumor cell lines. Tumor cells are shown to be distinguishable from normal mammary epithelial cells by morphology, by growth requirements, and by two markers: preferential expression of the HMFG-2 epitope on tumor cells and preferential retention in tumor cell mitochondria of the lipophilic fluorescent dye rhodamine 123. Differential fluorescence of HMFG-2 fluorescein-conjugated antibodies can be used as a basis for separation of normal and tumor cells in a fluorescence-activated cell sorter, as can differential retention of rhodamine 123.