STAT3 and gastric cancer: To verify the target of JAK1, we detected the phosphorylation of STAT1, STAT3 and STAT5 after JAK1 silencing (shJAK1‐1, shJAK1‐2) in GC cells using WB and found a significant decrease in phosphorylated STAT3 but not STAT1 or STAT5 (Figure S12a,b).