Abstract
Malignant transformation and mutation to ouabain resistance is induced in cloned M2 mouse fibroblasts in vitro by treatment with N-methyl-N''-nitro-N-nitrosoguanidine, the 3,4-diol of 7-methylbenz[a]anthracene and the 7,8-diol-9,10-oxide of benzo[a]pyrene. Transformation is more frequent than mutation; the ratio of transformation:mutation frequencies varied between 24 and 1118. The 9,10-diol-7,8-oxide derived from benzo[a]pyrene induced ouabain resistance without causing transformation. Induced ouabain-resistant clones did not behave like transformants and transformants did not exhibit ouabain resistance. The significance of these findings is discussed.