The selection of malignantly transformed rat liver cells using a hormonally defined medium.

A hormonally defined medium consisting of a 1:1 mixture of Dulbecco's modified Eagle's medium and nutrient mixture F12 supplemented with 50 micrograms/ml each of insulin and transferrin was found to grow late passage malignantly transformed cells of the RL-PR-C rat liver cell culture. The same medium formulation would not grow the early passage, normal, diploid counterpart of the RL-PR-C cell culture. When mixtures of the early and late passage cells were made, only the late passage cells would grow, thus providing a selection system for the late passage cells.