Analysis of the requirement for IL-23 in colitis-associated changes in extramedullary hematopoiesis showed a significantly reduced, although not completely absent, accumulation of GMP in the BM and periphery of T cell transferred Rag1−/−Il23p19−/− mice that developed mild intestinal inflammation (Figure S6D; Hue et al., 2006). The gene discussed is IL23A; the disease is gastroenteritis.