It is reported on recent recognitions in the activation of cellular oncogens by carcinogens, by exchange (translocation) of genes within various chromosomes as well as by infection by the proviruses DNA of retroviruses. Cellular oncogens can be activated by a mutation already by the exchange of a base in a desoxyribonucleotide. Mutations develop under the influence of carcinogens. The protein changed in a amino acid portion accepts transforming properties. The Epstein-Barr virus furthers the increase of the number of B-lymphocytes. In this case may take place a translocation of the oncogen c-myc of the chromosome 8 into the region of the gen-recombination for the formation of the polypeptide chains of the immunoglobulins in the chromosomes 2, 14, and 22, respectively: in this area is an acceleration factor for the transcription. Cellular oncogens may be activated by retroviruses also by the long terminal repetitive parts of the proviruses. Papilloma viruses relatively frequently appear in the carcinomas of the cervix.