Activity of NFkB transcription factors and signaling via STAT are frequently altered in gastric cancer cells. Mice lacking NFKB1 (Nfkb1–/– mice) develop invasive gastric cancer and their gastric tissues have increased levels of cytokines, such as interleukin (IL)6, IL22, IL11, and tumor necrosis factor (TNF), as well as increased activation of signal transducer and activator of transcription 1 (STAT1). We investigated whether these cytokines were required for STAT1 activation in gastric tissues of mice and critical for gastric tumorigenesis.