STAT1 and gastrointestinal stromal tumor: In human GIST cell lines and KitV558Δ/+ mouse GIST model, imatinib downregulates the expressions of IFNγ-related genes and IFNγ-induced PD-L1 expression by inhibiting STAT1 signaling pathway [35, 102], thereby reducing immune escape and enhancing antitumor immune response.