[Oncogenes and anti-oncogenes: the genetics of cancer].

Oncogenes and anti-oncogenes form two families of genes. If abnormal both may induce malignancies. They are distinguished, however, by two components. Oncogenes play a certain role in a given period of development (mainly during organogenesis). As soon as function has been completed they are inactivated. Aberrant reactivation even of one allele may induce tumors in different tissues independent of age. Anti-oncogenes on the other hand protect the organism, functioning mainly at the level of cell cycle regulation. Because one allele is sufficient for sustaining of adequate function both alleles of the anti-oncogene must be destroyed before tumor development is possible. Such a tumor will be tissue- and age-specific.