Abstract: Disclosed test cells are useful for evaluating the carcinogenicity of a compound using a transformation assay. The test cell preferably is transfected with an oncogenic viral recombinant nucleic acid molecule encoding a transforming protein. Cell growth is scored to identify the presence or absence of a transformation characteristic, such as formation of foci, loss of growth factor or serum requirements or anchorage independence. The development of such a transformation characteristic indicates that the compound being tested is carcinogenic.