|  | A 
            gene that contributes to the production of a cancer. Oncogenes are 
            generally mutated forms of normal cellular genes (proto-oncogenes). 
            A gene capable, when activated, of transforming a cell. Oncogenes 
            are found in the oncogenically activated state in retroviruses and 
            transformed cells and in their normal non-oncogenically activated 
            state in non-transformed cells in which they are called proto-oncogenes. |  |