FSTL1 and neoplasm: Specifically, interactions driving TRAIL-mediated apoptosis via the TNFSF10 (TRAIL)-TNFRSF11B ligand-receptor pair were identified between GZMAhigh NK cells and tumor subclusters (FSTL1+ tumor cells, XIST+ tumor cells, S100A4+ tumor cells, NNMT+ tumor cells, FOSB+ tumor cells, and NEAT1+ tumor cells), and between XCL1high NK cells and the same tumor subclusters (Fig. 5H).