A fault in the way cells signal to each other may be to blame for the development of a deadly form of skin cancer, researchers have found.
Melanoma is the most dangerous form of skin cancer
A team from the Marie Curie Research Institute has found 90% of malignant melanoma cells produce abnormally high levels of a protein called BRN-2.
The discovery could help differentiate between melanomas and less dangerous moles.
The protein seems to play a crucial role in cell division.
Malignant melanoma cells contained more than 20 times more of the protein than normal cells, the scientists found.
Lead researcher Dr Colin Goding said: "We found that BRN-2 is really important for melanoma growth.
"When we switch off BRN-2 in the lab, the cells grow much more slowly."
The researchers say their work shows that BRN-2 appears to be linked to two important signalling pathways in the cell, which carry instructions telling a cell when to divide and when to stop dividing.
Cancer results when this process of division spirals out of a control.
One pathway was wrongly activated all the time in 20% of melanomas, the other in
Dr Goding said: "BRN-2 is the key link between these pathways and melanoma
"These pathways are a bit like the accelerator cable in a car. When you press the pedal, the accelerator cable connects to the carburettor, controlling the speed of the engine.
"Imagine the accelerator is jammed on so that the engine can only run flat out. In a cancer cell, that's what happens - the cell machinery gets a signal telling it to divide all the time.
"It appears that it is BRN-2 that makes this crucial link to the `carburettor'."
Malignant melanoma kills an estimated 1,600 people in the UK each year.
The number of cases has risen with the boom in foreign holidays to sunny
Dr Tim Eisen, consultant oncologist at the Royal Marsden Hospital in London,
said: "This is a very important discovery of three reasons.
"First, it may help us tell the difference between moles that cannot cause further problems and melanomas that can.
"Second, it may help us to determine the risk of a further problem after somebody has had a melanoma removed.
"Third, this discovery is another important piece of information that shows us why melanomas behave the way they do and points to possible new ways of treating the disease."