This altarpiece was originally in the Chiesa dei Servi di Maria in Orvieto, and is the artist’s only known commission from the Order of the Servites of Mary. Surrounding the center image are the saints (from left) Paul, Lucy, Catherine, and John the Baptist. Each saint is surmounted by an angel, while above the center panel Christ displays his wounds.
Source: Eye of the Beholder, edited by Alan Chong et al. (Boston: ISGM and Beacon Press, 2003): 41.