ABSTRACT
Cellular oncogenes or protooncogenes have been implicated in the development and progression of human and animal tumors. To determine whether altered expression of protooncogenes are involved in the different steps of Friend erythroleukemias, we have investigated the expression of 18 protooncogenes in preleukemic and leukemic erythroid cells. The spleens from phenylhydrazine treated mice contain a majority of terminally differentiated erythroid cells, while Friend erythroleukemic cells are immature proerythroblastic cells blocked in an early stage of differentiation. Protooncogenes have been suggested to participate in the steps leading to malignant transformation. It is likely that more than one protooncogene abnormality is required to produce the malignant phenotype. The hypothesis that viruses may be involved directly or indirectly in the increase of c-myc transcription during viral infection has been recently suggested for the Epstein-Barr virus and the bovine leukemia virus.
