The v-myc oncogene

v-myc is the viral homolog of c-myc transduced by several acute transformin g retroviruses, many of which encode this gene as a Gag-Myc fusion protein, The v-myc oncogene can transform several lineages of mammalian and avian c ells either alone or in cooperation with other oncogenes, While the Gag por tion of the Gag-Myc fusion protein and the nuclear localization signal each appear to be dispensable for transformation, the N- and C-termini of the M yc sequence have been found to be essential for transformation. All v-myc g enes contain point mutations which seem to confer a greater potency to v-my c in the process of transformation, proliferation, and apoptosis, In v-myc- transformed myelomonocytic cells, secondary events occur, such as the expre ssion of colony stimulating factor-1 (CSF-1) which play a critical role in immortalization and subsequent tumor progression, Inhibition of the autocri ne loop of CSF-I was found to induce apoptosis in the immortalized cells, W hile overexpression of v-Myc blocks terminal differentiation of hematopoiet ic cells, this is not sufficient to block the differentiation of certain ne ural and skeletal muscle cells. Recent developments on the effects of v-myc on cell growth, transformation, differentiation and apoptosis are discusse d in this review.