TNFSF10 and gastric cancer: As K63‐linked polyubiquitination of caspase‐8 influenced the sensitivity of glioblastoma to TRAIL (Bellail et al., 2012), we next examined whether TRAIL induced K63‐linked polyubiquitination of caspase‐8 in gastric cancer cells and confirmed K63‐linked polyubiquitination of caspase‐8 in TRAIL‐resistant cells, but not in TRAIL‐sensitive MKN45 cells (Fig. S2A).