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Cancer-Fighting Gene Guards Against Sun Damage

Posted: March 8, 2007

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Differences in the MSH receptor explain differences in ability to tan. Redheads, for example, have a variant which doesn't respond at all to MSH, explaining why the Nicole Kidmans of this world don't turn a tawny bronze.

Fisher and his colleagues still didn't know, however, what happened within keratinocytes to stimulate MSH production.

"We knew that ultraviolet radiation causes MSH to be induced," Fisher said. "How is the ultraviolet radiation doing that? What is perceiving the radiation and translating that signaling into making more MSH?"

The key happens to be the tumor-suppressor gene known as p53, which is induced in almost every keratinocyte of human skin samples within an hour of being exposed to the sun's ultraviolet rays. "That activity is completely regulated by this protein," Fisher said.

The finding is biologically plausible, experts said.