By employing sST2-expressing pancreatic cancer Panc02 cells in an orthotopic implantation mouse model, we report here that, contrary to expectations, sST2 enhanced orthotopic tumor growth in immunocompetent but not IL-33 knockout mice, which suggests that IL-33-ST2L signaling inhibits pancreatic cancer growth. This evidence concerns the gene IL1RL1 and pancreatic neoplasm.