IL33 and cholangiocarcinoma: In this study, the level of IL-33 in CCA tissues was classified into 4 groups based on the level in either cancer cells or stromal CAFs: 1) low IL-33 in cancer cells and absence of IL-33 in CAFs (abbreviated as CL/FA), 2) low IL-33 in cancer cells and presence of IL-33 in CAFs (CL/FP), 3) high IL-33 in cancer cells and absence of IL-33 in CAFs (CH/FA), and 4) high IL-33 in cancer cells and presence of IL-33 in CAFs (CH/FP).