[Proto-oncogene expression in mouse leukemia induced by the Mazurenko virus].

: The expression of 8 protooncogenes was examined in different types of murine leukemia induced by Mazurenko virus. C-myc-specific RNA (2, 3 kb and 1.8 kb) was revealed only in tissues of mice with thymomas (T-cell leukemias) but not with generalized leukemias. 1.4 kb Ha-ras RNA transcripts were observed in all RNA species from leukemic mice. The highest expression of the above oncogenes was noted in thymus and lymph nodes, in spleen and liver the expression was lower. Ki-ras, abl, fos, myb, erb and B-lym-specific RNA expression was not observed in any of the tissues tested. The expression of C-myc RNA is believed to be the result of C-myc activation due to provirus integration.