JAK1 and gastric adenocarcinoma: In stomach adenocarcinoma (STAD), 1/293 (0.3%) MSS samples, 2/63 (3.2%) MSI-L samples, and 20/85 (23.5%) MSI-H samples had a frameshift in JAK1, which was also statistically significant when comparing MSS and MSI-H groups (Fig 2F, P < 0.0001, Fisher’s exact test).