Dexamethasone and anti-fas induce and IL-6 inhibits TRE-CAT activity. 8226 cells (▨) or UCLA #1 cells (□) were transfected with the AP-1–dependent transcriptional reporter 3× TRE-CAT and treated with anti-fas (0.5 μg/mL), dexamethasone (10⁻⁶ mol/L), IL-6 alone (1,000 U/mL), or the combinations of dexamethasone + IL-6 or anti-fas + IL-6. Treatments were for 60 minutes and cells were lysed after 24 hours; CAT activity was measured with (¹⁴C) chloramphenicol as substrate. Data represent means ± SE of three independent trasnfections and are expressed as fold increase in activity compared with control cells that received the TRE-CAT vector but no drug treatment.