[Provirus structure and expression in rat cell lines transformed by the avian sarcoma virus].

Two type of exogenous action on transformed cells have been investigated. The first system includes clones of TWERC cells transformed by Rous sarcoma virus and cultivated in the presence of 5-bromodeoxyuridine. The second system consists of spontaneously transformed rat cells Sam IV superinfected with avian sarcoma virus B-77. In these cell lines and clones the structure of the provirus and its expression have been analyzed by different molecular probes.