An unintentional discovery could provide a cure for baldness.
Researchers at Manchester University were testing a drug on hair follicles when they found out it had caused a biological stress response that shut down the growth process.
The response slows down non-essential bodily functions like hair growth in the event of an infection but the process can go awry and kill off scalp cells permanently.
Boffins think that halting the reaction with a drug could prevent balding.
Dr. Talveen Purba, author of the study, said: "This stress response may be implicated in a number of hair loss disorders, including pattern hair loss.
"We're incredibly hopeful that targeting it could lead to new treatments."
He added: "A complete reversal is unlikely and you probably wouldn't have a lot of luck trying to regenerate hair in people who have completely lost it.
"But if you can catch it as they are actively losing it, it's possible you could stop the process.
"Our key next steps are to confirm this is happening in people, then to work out if we can control it."
Tagged in Hair Loss