[Recent findings on the effect and role of oncogenes in carcinogenesis].

The tumourous phenotype of cells may be induced by physical, chemical and biological factors. All have the same target, the cell genoma where they can produce minor (e.g. point mutations) or major changes (e.g. reconstruction--chromosomal aberrations, or gene insertion--oncoretroviruses). At present it may be assumed that these factors participate in the activation of proto-oncogenes (cellular oncogenes, c-onc) or in the inactivation of yet not well recognized "tumour suppressor" genes, so-called "anti-oncogenes". So far it was found that deletion of both alleles of "suppressor" genes causes the development of several recessive hereditary tumours (retinoblastoma, Wilms tumours etc.). Activation of proto-oncogenes (by point mutation, amplification, translocation) was found in a number of advanced primary tumours and in metastases. Probably activation of proto-oncogenes will play a more important part in the development of "acquired" tumours and in their progression. The problem of the mutual relationship of proto-oncogenes and "anti-oncogenes" remains so far obscure and controversial.