Integration of oncogenic viruses in mammalian cells

It is clear from result presented that the genomes of oncogenic viruses can integrate in different sites in the same or different chromosomes in different viral-transformed cells. It is not clear, however, whether the viral genomes integrate into specific sites or at random in the mammalian cell genome. Nucleotide sequencing of the cellular DNA sequences flanking the viral integration sites and the use of recombinant plasmid DNAs containing a selectable gene (thymidine kinase) and the tumor virus genome should result in a better understanding of the molecular mechanism of the integration of oncogenic viruses in the cellular genome.