A system employing a minimal defined medium for the selection of tumorigenic cells.

Populations of normal and tumorigenic epithelial cells were plated in normal (serum supplemented) and a minimal defined medium. The ability of cells to grow in the minimal defined medium vs. the normal medium was related to their tumorigenic ability. All of the clones that were capable of growth in the minimal defined medium demonstrated tumorigenic ability. None of the normal clones survived in the minimal defined medium. As expected, some of the tumorigenic clones could not grow in the minimal medium. However, at no time did a clone that grew in the minimal defined medium fail to demonstrate tumorigenic ability. This validated that this system can be an animal-free means for selecting tumorigenic epithelial cells out of a mixed population.