TRAF6 and thymoma: When bound to the IL-18R, IL-18 induces the formation of an IL-1R-associated kinase (IRAK)/TNF receptor-associated factor-6 (TRAF-6), a multipart structure that has stimulatory activity for nuclear factor κB (NF-κB) in Th1 cells [47] and in EL4/6.1 thymoma cells [31,64].