Francesco Ubertini (Italian, 1494? – 1557) studied and worked with some of the great artists of the late Italian Renaissance. In 1540, Ubertini joined the official artists serving the nobles in the court of Duke Cosimo I de' Medici (ruled 1537 - 1574), where his art gained great favor.
Ubertini’s paintings gained popularity for his “borrowings:” figures, backgrounds, and patterns borrowed from famous paintings and prints, changed slightly, brightly colored, and incorporated into his own paintings. They became “I Spy”-style games for the nobles, who attempted to demonstrate their artistic knowledge by recognizing and identifying these borrowings.
The bearded figure on horseback on the left side of St. Paul in MAG's painting is believed to be Ubertini's self-portrait.