The team found that when gene p53 is defective, it loses its ability to regulate healthy cells and suppress cancer.
For two decades, gene p53 is known to be the master gatekeeper that controls all cancer development.
"Until now, we thought these cousins (TAp73 protein isoforms) were not involved in cancer. Our results prove that they are. This is fundamental to understanding every human cancer and furthering the science," said lead researcher Dr. Tak Mak, director of The Campbell Family Institute.
The new discovery has opened up a critical new branch of scientific inquiry.
In the lab, Dr. Mak and his team challenged traditional thinking about the role of these proteins.
"Before, scientists studied only whether these proteins were present or absent. We decided to study how they interact with each other and discovered that they actually have a split personality," Mak said
"When we turn one 'on' or 'off', the other changes behaviour and becomes part of the cancer-causing process. The key is understanding the ratio of the interaction."
"The next step is to understand how the ratio affects cell division that leads to human cancer," Mak added.
The findings are published online in the journal Genes and Development.