A protein that protects the body from tissue damage also increases the risk of tumours, says a study.
Researchers at Washington University School of Medicine in St. Louis tested the protein Bcl-xL that helps the body's healthy cells survive the effects of toxic chemotherapeutic agents.
They also found that the protein encourages the growth of tumours in mice exposed to a carcinogen, reports the science portal eurekAlert.
The study compared the effect of urethane, a lung-specific carcinogen, on two sets of mice -- wild-type mice, which have two functional genes that express Bcl-xL, and transgenic mice that have only one functional gene expressing the protein.
Because they have only one of the genes, transgenic mice produce less Bcl-xL. After exposure to urethane, 40 percent of wild-type mice developed seven or more lung tumours, while no transgenic mice developed more than seven tumours.
Furthermore, wild-type mice on average had larger tumours than transgenic mice.