STAT5-dependent JAK2 signaling is required for anti-inflammatory cytokine production and IEC repair, and mutations or single nucleotide polymorphisms in JAK2-STAT5 increase susceptibility to colitis and ileal Crohn’s disease (Gilbert et al, 2012a; Huang et al, 2015; Chuang et al, 2016). Here, JAK2 is linked to colitis.