Deficiency of all three IAPs (c1LysMcrex−/−c2−/− BM chimeras), but not XIAP and cIAP2, in the myeloid compartment led to accelerated and exacerbated K/B × N arthritis (Fig. 9a–c and Supplementary Fig. 8f,g). The gene discussed is XIAP; the disease is Arthritis.