SPHK1 and neoplasm: A gene ontology (GO) analysis of genes positively correlated with SPHK1 not only revealed the expected enrichment of genes with biological activities consistent with known tumor-associated S1P functions, including anti-apoptosis, vascular and endothelial cell development, and cytokine regulation (Figure 1A), but also the significant enrichment of GO terms associated with macrophage functions, including macrophage activation, macrophage migration, and the regulation of phagocytosis.