SPP1 and hepatocellular carcinoma: The heatmap (Fig. 2K) showed that elevated VEGFA–VEGFR expression was correlated with increased GP73 in cell clusters 6, 9, 16, 17, 22, 23, and 24, while cell clusters 3, 12, and 22, rich in vascular endothelial cells, strongly interacted with overexpressed GP73 HCC cells through the receptor–ligand interactions VEGFA–VEGFR1/R2, TGFB1–(TGFBR1 + TGFBR2), SPP1–(ITGAV + ITGB1), and ANGPTL4–CDH5.