PROTOONCOGENES IN PLANTS - WIDESPREAD CONSERVED GENES FOR WHICH ROLES

The results obtained during the last decades on the understanding of t he abnormal growth properties of cancerous cells have brought new insi ghts on the control of growth, differentiation and development of mult icellular organisms, by the discovering of ''oncogenes'', which are im plicated in these phenomenons. The development of cancer is now consid ered as a consequence of abnormal expression or function of set of cel lular genes, which become ''oncogenic''. These genes were identified b y their ability to induce neoplastic transformation. They are consider ed to be mutant forms of normal cell-genes, called proto-oncogenes. Pr oto-oncogenes and related genes and proteins have been found in numero us multicellular organisms, including human, animal, sponge, yeast and plant. This widespread conservation indicate that these genes and the ir products play probably essential biological roles. Because of the i mportance of these genes, that could play central roles in regulatory systems governing the life of a normal cell, we present here a rapid r eview on the main known animal proto-oncogenes, on their established o r supposed functions and we try, on the bases of the related ones, dis covered in plants, to propose a general scheme for the living cell.