Illustration of how a normal cell is converted to a cancer cell, when an<unk>  becomes activated An<unk>  is a gene that has the potential to cause cancer. In tumor cells, these genes are often mutated, or expressed at high levels. Most normal cells will undergo programmed form of rapid cell death (apoptosis) when critical functions are altered and malfunctioning. Activated<unk> s can cause those cells designated for apoptosis to survive and proliferate instead. Most<unk> s began as proto-oncogenes: normal genes involved in cell growth and proliferation or inhibition of apoptosis. If, through mutation, normal genes promoting cellular growth are up-regulated (gain-of-function mutation), they will predispose the cell to cancer; thus, they are termed<unk> s". Usually multiple<unk> s, along with mutated apoptotic or tumor suppressor genes will all act in concert to cause cancer. Since the 1970s, dozens of<unk> s have been identified in human cancer. Many cancer drugs target the proteins encoded by<unk> s.
Oncogene
Mitogen
Anticancer gene
Tumor antigen
Metastasis suppressor
Carcinogen
Adjuvant
Gene