Presence of fibroblast-transforming genes in normal DNA of several mouse and rat strains.

Cellular DNA of the inbred mouse strains BALB/c, C3Hf, C57BL, CBA, DBAf , GRS and ND2 and the inbred rat strains BN, SD and WAG was shown to oncogenically transform murine fibroblasts of the continuous cell line BALB/3T3. Subcutaneous inoculation of transformed cells into BALB/c mice led to the rapid development of sarcomas. For transformation the DNA had to be fragmented to a size smaller than 23 kilobase pairs (kbp), with a lower limit of 6.5 kbp. No transforming virus could be rescued from the transformed lines by infection with a murine leukemia virus.