[Oncogenesis in XXXX ].

@entity19 @entity5
Oncogenesis in @entity19 is at present a model, most adequately reflecting the natural conditions of @entity5 development. One of more important traits of this model is that it allows to study malignant growth simultaneously at all the structure-function levels in the context of the whole organism. This paper is a review of results of a series of experiments in which the localization of @entity5 was dependent or independent on the tissue specificity of a promoter, as well as development of @entity5 with the use of viral regulatory sequences in genetic constructions. It has been shown that although a transgene is expressed in most of the tissues, @entity5 develop in some particular tissues only. These observations are interpreted by some authors in favour of the concept of multistep cancerogenesis. In this view, of primary importance are the results of studies on oncogenesis in @entity19 , which contradict this concept and are regarded by their authors as an evidence of the possibility of a one-step transformation of normal cell into malignant one. The analysis of the obtained material enabled us to put forward an assumption that the key role in oncogenesis is played not only by certain genetic disturbances, but also by multi-level homeostatic mechanisms. Apparently, it is just the @entity19 with cellular or viral oncogenes in their genome that represent a more adequate model for the detection of certain molecular-biological mechanisms underlying these disturbances. Also, of much importance is abundant material accumulated by now on oncogenesis of @entity19 which shows a possibility of the effective use of various genetic constructions with prokaryotic and eukaryotic regulatory sequences, a possibility to induce not only @entity5 of some particular tissues, but also multiple hyperplastic and neoplastic changes in one and the same @entity19 . Development of @entity5 in such @entity19 can be regarded as a model of different types of @entity5 .
