CD47 and cancer: Compared with normal cells, CD47 is highly expressed in many cancer cells or tissues, such as non-Hodgkin lymphoma cells [14], acute lymphoblastic leukemia cells [15], bladder tumor-initiating cells [16], breast cancer cells [17], myeloma cells [18], hepatocellular carcinoma [19], etc. Recent studies have found that tumor cells evade the phagocytosis and killing effect of macrophages by overexpressing CD47 and induce immune escape of tumor cells [12, 20, 21].