Proto-oncogenes are phylogenetically ancient genes which are involved in the normal controls of cell proliferation. Under
some circumstances, these normal genes may be altered and generate qualitatively or quantitatively abnormal gene products.
Under these circumstances the proto-oncogenes may be involved in the pathogenesis of malignant diseases.
Key-words Cancer - Carcinogenesis - Oncogenes - Oncoproteins - Retroviruses