According to his half-brother Alessandro, he made the acquaintance of the humanist Benedetto Lampridio, Antonio Tebaldeo, Carlo Gualteruzzi, and Pietro Bembo, in addition to Angelo Colocci, who considered Marcello his best friend. [En 31]
Bembo held Cervini in considerable esteem allegedly because of his learning, prudence, and good judgement, but just as likely because of favors he had done Bembo in the past.
Colocci (1474–1549), who similarly was enriched through papal favors and offices, depended upon Cervini and others for translations and interpretations of Greek sources to augment his considerable antiquarian interests. He owned an important collection of statues and other antiquities, in addtion to a well-known library stocked with scriptural texts, the Latin and Greek Fathers, and the works of modern authors like Enea Silvio Piccolomini and Pietro Balbi. Cervini picked over this collection after Colocci's death, apparently under orders from Paul III, with a view to increasing the holdings of the burgeoning Vatican library. Colocci also named Cervini as executor of his will.