Art historian Silvano Vinceti gestures as a photo of Italian artist Leonardo da Vinci's "Mona Lisa" painting is projected in the background during a press conference in Rome on Wednesday, Feb. 2, 2011. Mr. Vinceti said the main influence and model for the "Mona Lisa" was a male apprentice of Leonardo da Vinci, Gian Giacomo Caprotti, known as Salai, who worked with Leonardo for years starting in 1490. (AP Photo/Andrew Medichini)

Photo by: Andrew Medichini

Art historian Silvano Vinceti gestures as a photo of Italian artist Leonardo da Vinci's "Mona Lisa" painting is projected in the background during a press conference in Rome on Wednesday, Feb. 2, 2011. Mr. Vinceti said the main influence and model for the "Mona Lisa" was a male apprentice of Leonardo da Vinci, Gian Giacomo Caprotti, known as Salai, who worked with Leonardo for years starting in 1490. (AP Photo/Andrew Medichini)