Italian sculptor and medallist. He was the son of Isaia da Pisa. Some scholars have followed Vasari in suggesting that he was trained by his father or by Paolo Romano, but Isaia stopped work and Paolo died too early to have had any significant influence on him. It is likely that he studied with Andrea Bregno, who worked in Rome from 1446 to 1506. He may have been in Urbino before 1482, working at the Palazzo Ducale with the Lombard master Ambrogio d'Antonio Barocci. Several doorframes in the palazzo have been attributed to him. He then probably went to the Este court at Ferrara. In 1490 he carved a portrait bust of Beatrice d'Este (Paris, Louvre), the daughter of Ercole I d'Este, Duke of Ferrara, for her betrothal to Ludovico Sforza, Duke of Milan. The attribution of this bust derives from a letter of 12 June 1491 from Isabella d'Este, requesting that Ludovico send Giovanni Cristoforo, who had done Beatrice's portrait, to Mantua to work for her. The bust is inscribed with the imprese of a sieve surrounded by a diamond ring. The sieve was a symbol of Ludovico, the diamond of Ercole; entwined they suggest marriage and the hope of fertility. This bust is the sculpture most securely attributed to Giovanni Cristoforo and, with his medals, provides the basis for the assessment of his style. From Ferrara he travelled to Pavia to work on the Certosa. He precipitated a change in Lombard sculpture, influenced by his own courtly style indebted to Roman imperial art. //