SIRPA and neoplasm: When CD47 binds to SIRPα, it transmits the “do not eat me” signal to macrophages, negatively regulates phagocytosis, and weakens the presentation of tumor antigens to T-cells, thus reducing the antitumor effect mediated by macrophages and cytotoxic CD8+ T-cells [103] and helping tumor cells escape immune surveillance and phagocytosis [104,105].