Phenotypic transformation of normal rat kidney cells: a model for studying cellular alterations in oncogenesis

The growth characteristics of cells in culture change dramatically upon tumorigenic transformation. By the use of selective culture media supplemented with growth factor-inactivated serum, the changes in requirements for externally added polypeptide growth factors can readily be assessed. Certain nontumorigenic cell lines, including normal rat kidney (NRK) fibroblasts, can obtain the growth characteristics of a tumor cell when they became phenotypically transformed by addition of specific combinations of growth factors. This cell system provides a very attractive model for studying cellular alterations upon transformation, in particular for analyzing the molecular basis of density-dependent inhibition of growth (contact-inhibition).