SIRPA and neoplasm: Accordingly, mechanical barriers [48] (e.g., stromal fibrosis [49], vascular formation [50]) and functional barriers [48] (e.g., metabolic barriers [51], TGF-ß [52], CD47-SIRPalpha signaling axis [53], immune checkpoint expression [23]) along the invasive margin were found preventing TILs from entering the tumor center in the immune excluded phenotype.