SIRPA and neoplasm: The other molecular mechanism involved in the CD47-signal regulatory protein α (SIRPα) pathway is namely that, engagement of SIRPα expressed on TAMs with CD47 overexpressed on tumor cell surface can activate the Src homology region 2 domain-phosphatases 1/2 (SHP-1/2) in TAMs, thereby resulting in a “eat-me-not” signal and inhibition of macrophage-phagocytosis 34.