FCGR2B and neoplasm: In addition, down-regulation of CD16, but not CD32a/b, was observed on in vitro induced MDSC with FcγR: hIgG1 ligation (Fig. 4c) and monocytes co-cultured with cetuximab-coated tumor cells (Fig. 5e), indicating CD16 is internalized after interacting with the hIgG1 Fc portion of cetuximab and hIgG1 mainly interact with CD16 instead of CD32a or CD32b.