Apoptosis induced by DNA damage and other stresses can proceed via expression of Fas ligand (FasL) and ligation of its receptor, Fas (CD95). We report that activation of the two transcription factors NF-κB and AP-1 is crucially involved in FasL expression induced by etoposide, teniposide, and UV irradiation. A nondegradable mutant of IκB blocked both FasL expression and apoptosis induced by DNA damage but not Fas ligation. These stimuli also induced the stress-activated kinase pathway (SAPK/JNK), which was required for the maximal induction of apoptosis. A 1.2 kb FasL promoter responded to DNA damage, as well as coexpression with p65 Rel or Fos/Jun. Mutations in the relevant NF-κB and AP-1 binding sites eliminated these responses. Thus, activation of NF-κB and AP-1 contributes to stress-induced apoptosis via the expression of FasL.