Oncogenes and tumor-suppressor genes - 2 different looks of the same gene.

Dominant oncogenes and recessive tumor suppressor genes are widely implicated in the pathogenesis of human neoplasia. Several recent experimental findings suggested that an oncogene and a tumor suppressor gene can share a similar ontogeny from the parental normal 'in vivo' gene. At least three mechanisms have been demonstrated to be responsible for this ambivalent expression: the mutations located in different regions of the gene, transcriptional and post-transcriptional events (especially alternative splicing) and cell- and/or time-dependent control of gene expression. There are also evolutionary explanations for the existence of such genes with ambivalent expression.