TNFRSF9 and nasopharyngeal carcinoma: Using rhCD137L-ST complexes, we obtained similar results as with rhCD137L-MSNs, in which rhCD137L-ST promoted a greater cytolysis of both CD137-expressing (C666-CD137 and HK1-CD137) and CD137-deficient (C666 and HK1) NPC cell lines, than unconjugated urelumab and utomilumab, when added at an equal protein concentration (Figure S3C-D).