SPP1 and neoplasm: To explore the biological features associated with this unique tumor-macrophage link, we compared single-cell transcriptomic profiles of TAMs from tumors with or without the presence of LGALS9-SLC1A5 and SPP1-PTGER4, and found 4 main subtypes of TAMs, i.e., c1 (proliferative), c2 (inflammatory), c3 (restorative), and c4 (CLEC9A+WDFY4+) (Fig. 7h).