We recently showed that TNF induces accumulation of reactive oxygen species (ROS) that mediates necrosis in murine embryonic fibroblasts (MEFs) derived from TRAF2- and TRAF5-double deficient (DKO) mice. To elucidate the defects that subsequently cause accumulation of ROS in DKO MEFs, we compared gene expression profiles of wild-type and DKO MEFs before and after TNF stimulation using cDNA microarrays. Interestingly, many antioxidant enzymes are induced by TNF in wild-type MEFs, induction of these genes is impaired in DKO MEFs. Taken that TNF induces accumulation of ROS in DKO, but not wild-type MEFs, upregulation of antioxidant enzyme(s) might play a crucial role in elimination of ROS.