ABSTRACT
The first member of the myc gene family, the v-myc gene, was isolated from the avian myelocytomatosis virus MC29. Its cellular homologue, the c-myc gene, is evolutionary well conserved between different species. Two other closely related genes, N-myc and L-myc, have also been cloned and characterized. In situ hybridizations on tissue sections have indicated that even within one tumor, the levels of expression of the N-myc gene can vary between individual cells, being highest in undifferentiated neuroblasts. Thus, it is possible that those tumor cells which have amplified the N-myc gene grow faster than the rest of the tumor cells and are therefore diagnosed at an advanced stage. Several m-acting regions mediating transcriptional regulation by positively or negatively acting factors have been demonstrated in the upstream region of the human c-myc gene.
