The purpose of the project is to understand the mechanism of in vitro transformation and in vivo tumorigenesis of Indian muntjac cells infected by tumor viruses. A. We have succeeded in isolating the transformed and tumorigenic Indian muntjac cells with stable diploidy (2n equals 6 in the female and 7 in the male). B. We have determined the site(s) of integration of the src gene in the DNA of the clonal isolates of the transformants and found that the src gene DNA sequence of mouse sarcoma retrovirus integrates at multiple and different sites of the host genomes with the specific recombination site of the viral genome.