title: Myc oncogenes: the enigmatic family.
abstract: The myc family of proto-oncogenes is believed to be involved in the establishment of many types of human malignancy. The members of this family have been shown to function as transcription factors, and through a designated target sequence bring about continued cell-cycle progression, cellular immortalization and blockages to differentiation in many lineages. However, while much of the recent work focusing on the c-myc oncogene has provided some very important advances, it has also brought to light a large amount of conflicting data as to the mechanism of action of the gene product. In this regard, it has now been shown that c-myc is effective in transcriptional repression as well as transcriptional activation and, perhaps more paradoxically, that it has a role in programmed cell death (apoptosis) as well as in processes of cell-cycle progression. In addition, particular interest has surrounded the distinct roles of the two alternative translation products of the c-myc gene, c-Myc 1 and c-Myc 2. The intriguing observation that the ratio of c-Myc 1 to c-Myc 2 increases markedly upon cellular quiescence led to the discovery that the enforced expression of the two proteins individually showed that c-Myc 2 stimulates cell growth, whereas c-Myc 1 appears to be growth suppressing. Clearly, the disparities in the activities of c-Myc, together with the consistent occurrence of mutations of c-myc in human malignancies, means that, although reaching an understanding of the functions of the myc gene family might not be simple, it remains well worthy of pursuit.
authors.affiliation: The Beatson Institute for Cancer Research, Glasgow, Scotland, U.K.
authors.forename: K M
authors.initials: KM
authors.lastname: Ryan
authors.forename: G D
authors.initials: GD
authors.lastname: Birnie
mesh_terms: D000818:Animals; D001483:Base Sequence; D002471:Cell Transformation, Neoplastic; D016259:Genes, myc; D006801:Humans; D005810:Multigene Family; D009369:Neoplasms / Q000235:genetics*; D016271:Proto-Oncogene Proteins c-myc / Q000235:genetics / Q000378:metabolism; D013379:Substrate Specificity; D014157:Transcription Factors / Q000378:metabolism; D014158:Transcription, Genetic
chemical_list: D016271:Proto-Oncogene Proteins c-myc; D014157:Transcription Factors