HLA-F and neoplasm: Notably, three immunologically relevant ligand-receptor pairs, including major histocompatibility complex, class I, A-amyloid beta precursor-like protein 2 (HLA-A_APLP2), biglycan-toll-like receptor 4 (BGN_TLR4), and β2 microglobulin-human leukocyte antigen-F (B2M_HLA-F), were significantly co-expressed in the tumor centers and at the junction of tumors and normal tissues (Figure 11B).