a gene that disposes normal cells to change into cancerous tumor cells
"Doctors discovered that the patient's aggressive lung growth was driven by an activated oncogene forcing healthy tissue to transform into a malignant tumor."
Any gene that contributes to the conversion of a normal cell into a cancerous cell when mutated or expressed at high levels.
"The researcher discovered that a specific oncogene had become overactive, driving the liver cells to divide uncontrollably and form a tumor."