Oncoproteins are any proteins coded by an oncogene involved in the regulation or synthesis of proteins related to tumorigenic cell growth. They are generally mutated or expressed at high levels in cancer cells. These proteins help normal cells transform into cancer cells. Some oncoproteins are accepted and used as tumor markers. Since the 1970s, many oncogenes have been identified in human cancer. Many cancer drugs are designed to target the proteins encoded by oncogenes.