CD47 and leukemia: Tumor cells may need to express additional pro-phagocytic signals such as SLAMF7 with Mac-1 [92] and calreticulin induced by azacitidine, [93] or additional activation of macrophages via Fcγ receptor activation by the Fc region of a monoclonal antibody targeting CD47 or by a second agent targeting leukemia cells (e.g., CD33).