Importantly, the guidelines apply to the federal school lunch and breakfast programs. Under the new Guidelines, schools will need to offer less-salty foods and more fruits, vegetables and whole grains.

Although the Guidelines does not give specific limits for trans fat and added sugars, its intent is clear. It advises people to consume as little trans fat as possible. It also recommends choosing foods and beverages with little added sugars or caloric sweeteners. The Guidelines states that only eight teaspoons of added sugars ”less than in a can of Coke ”fit into a healthy moderate-fat diet. In a higher-fat diet, there ™s no room for any added sugars.

As good as the Dietary Guidelines is, it will do little to improve the public ™s health without vigorous efforts to improve the food environment and communicate them with the public. To support the guidelines ™ healthy-weight goals, Congress needs to provide the Centers for Disease Control with greatly increased funding for programs that promote nutrition and activity and pass laws requiring calorie labeling on menus at chain restaurants and shielding kids from junk-food marketing. Because industry has done little voluntarily to implement past Dietary Guidelines for Americans, government regulatory agencies need to take such actions as limiting the salt content of processed foods, eliminating the use of partially hydrogenated oils, and lowering the current limits on fat in processed meats.

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Paul Yuan, a post-doctoral fellow in Chin's Rhode Island Hospital lab and the lead author of the paper, painstakingly mutated 47 lysine amino acids and tested each one in cultured cells to see if it activated STAT3. Using this method, Yuan was able to isolate the culprit: Lys685, one of as many as 780 amino acids that are strung together to make the protein.

Yuan corroborated the finding by testing both a normal and mutated version of STAT3 in a mass spectrometer. The machine smashes the protein into amino acids then sequences these building blocks. The work took nearly two years to complete.

Chin said the research provides an important target for drugs in treating breast and prostate cancers that are common in the United States. According to the American Cancer Society, an estimated 217,440 Americans were diagnosed with breast cancer and 230,110 were diagnosed with prostate cancer in 2004.

"Finding a drug to block both tyrosine phosphorylation and lysine acetylation of STAT3 protein should be a more effective cancer treatment," Chin said.

The research team also included Ying-jie Guan, a post-doctoral fellow in the lab, and Devasis Chatterjee, an assistant professor (research) of Medicine at Brown Medical School.

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