In colitic mice, mesenteric lymph node (MLN) DCs express elevated amounts of CD40 and CD134L, and blockade of either the CD40-CD40L (Uhlig et al., 2006b) or the CD134-CD134L (Malmström et al., 2001) pathway inhibits colitis, illustrating that DCs promote colitogenic responses. Here, CD40 is linked to colitis.