CD47 and familial pancreatic carcinoma: Clinical studies have shown that CD47, as a natural immune checkpoint molecule, is highly expressed in cancer tissues such as gastric cancer, leukemia stem cells, Hodgkin’s lymphoma, breast cancer, cervical cancer, pancreatic cancer, and non-small cell lung cancer, and even the level of CD47 expression in tumor stem cells is higher than that in tumor cells (40–46).