In vitro transformation assays for chemical carcinogens.

A variety of in vitro mammalian cell assays, designed specifically for the identification of carcinogenic compounds, have been in operation for more than a decade. Although no individual transformation system has won universal acceptance during this time, recent advances have led to the improved reliability and sensitivity of a number of these short-term tests. The underlying problems associated with the most widely used assays are identified and new developments in this rapidly expanding field are noted and discussed.