Oncogene Concept: An oncogene is a gene that when mutated or expressed at abnormally-high levels contributes to converting a normal cell into a cancer cell a Cellular oncogene(c-onc) proto-oncogene( proto-onc): in normal physiologic version Oncogene altered in cancer 口 iral oncogene(-oncOncogene Concept: An oncogene is a gene that when mutated or expressed at abnormally-high levels contributes to converting a normal cell into a cancer cell.  Cellular oncogene (c-onc)： --- proto-oncogene （proto-onc）：in normal physiologic version --- Oncogene：altered in cancer  Viral oncogene （v-onc）