CD47 functions as a ligand for signal regulatory protein α (SIRPα) expressed on the cellular surface of innate immune cells including macrophages [14], and behaves as a dominant macrophage checkpoint [15,16,17], thereby providing a potent “do not eat me” signal to the macrophages that enables cancer cells to evade immunosurveillance from the innate immune system [15,16,17]. Here, CD47 is linked to cancer.