**2.5 CD47**

CD47 is a transmembrane glycoprotein that is widely expressed in human tissues. CD47 also functions as a marker of "self" on host cells within an organism. When expressed, CD47 binds to SIRPα on the surface of circulating immune cells to deliver an inhibitory "don't eat me" signal [24]. Higher expression of CD47 has been demonstrated in LSCs [25, 26]. Anti-CD47 antibody treatment has also been shown to act synergistically with cytarabine (Ara-C) chemotherapy in a model of AML. While Ara-C effectively eliminated TSP-1 cancer cells in the proliferative phase, anti-CD47 antibodies were putatively able to target quiescent LSCs that were not susceptible to Ara-C treatment but highly expressed CD47 [27].
