The painting has been in headlines before, starting in the early 20th century. And it's not unknown to a foreign audience: It was shown in Japan last year before the foundation's research was finished.
Experts say Thursday's unveiling was designed to draw more attention and scrutiny from worldwide art experts about whether it's authentic: A start more than a finish.
The Isleworth painting first came to public light after British art collector Hugh Blaker found it in the home of a nobleman in Somerset, England before World War I, said Robert Meyrick, head of the art school at Wales' Aberystwyth University.
Blaker bought the painting and took it to his private studio in Isleworth outside London. U.S. and British newspapers, meanwhile, speculated even then that it might be a da Vinci. But at that time only art experts -- not high-tech science tests like the ones conducted by the foundation -- could judge its possible bona fides.
During World War II, Blaker shipped the painting to Boston's Museum of Fine Arts for safekeeping, the foundation said. In 1962, it was bought by U.S. collector Henry Pulitzer. When he died in 1979, his reported mistress -- Elisabeth Meyer -- inherited it, but it remained in a Swiss bank vault.
After she died, an "international consortium" -- which the foundation declined to identify -- bought the painting in 2008, according to the group's chronology. The foundation was set up two years later, determined to try to show that it was a real da Vinci.
The Mona Lisa Foundation's members are more from the business world than the art world. Participating in Thursday's show was David Feldman, an Irish-born stamp auctioneer; his brother Stanley, an art historian who was the main author of an extensive book on the "Isleworth Mona Lisa"; and Markus Frey, a lawyer in Zurich who is the foundation's president.
The foundation and its backers paid "several million" to conduct research tests -- forensic analysis, carbon-dating and computerized regression analysis -- on the work, Feldman said. He wouldn't say how much the painting was bought for in 2008.
Carlo Pedrotti, one of the world's most eminent scholars on da Vinci, hailed the foundation's "extraordinary contribution to scholarship."