SIRPA and neoplasm: These studies generally focus on the role of CD47 as a passive counter-receptor for SIRPα, which protects tumor cells from phagocytic clearance or antigen presentation via SIRPα-expressing macrophages, neutrophils and dendritic cells (Gardai et al., 2005; Chao et al., 2010; Willingham et al., 2012; Matlung et al., 2017).