This undated photo provided by Revivicor, Inc., a unit of United Therapeutics, shows a genetically modified pig. U.S. regulators have approved a genetically modified pig for food and medical products, making it the second such animal to get the green light for human consumption -- but United Therapeutics, the company behind it says there are no imminent plans for its meat to be sold. (Revivicor, Inc. via AP)
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