MAC-1 is a complement receptor (CR3) containing α-subunit CD11b (αm) and β-subunit CD18 (β2); it interacts with ITAM,175 FcRγ and DAP12 to mediate immune cell activation by Src, Syk, and Bruton’s tyrosine kinase (Btk) intrinsic signaling175 and enhance phagocytosis via the IgG-mediated FcR pathway (Fig. 4b).176 The expression of MAC-1 on macrophages is necessary for SLAMF7-dependent phagocytosis of cancer cells.175 Whether SLAMF7 is required for CD47-mediated phagocytosis is controversial. Here, BTK is linked to cancer.