[Malignant cell transformation and oncogenes].

In genome of all transforming retroviruses special genes (oncogenes) have been identified which play a key role in malignant conversion of the cells, infected with these viruses. The homologues of these genes (protooncogenes) are persist in all normal cells. During transformation protooncogenes can be activated as a result of one of following processes: insertion of promotor-like elements, mutations, translocations, amplifications or rearrangements. Using transfection technique the transforming genes were isolated from different human tumors. The activation of one of the cellular oncogenes may switch on the other genes and malignant cell transformation may be characterized as a multifactor and multistage process.