PTGER4 and neoplasm: Gene expression levels of ANXA1-FPR3, NECTIN2-TIGIT, CXCL8-NR3C1, LGALS9-HAVCR2, C5AR1-RPS19, and SPP1-PTGER4 pairs were higher in sender and receiver cells derived from tumor tissue compared with normal tissue (Figure 7d, Supplementary Figure S15b).