Secreted IL-1Ra promoter transfections. HepG2 cells were transfected with a construct containing the 294-bp sIL-1Ra promoter fragment coupled with the luciferase reporter gene. The cells were then cultured in the absence (control) or presence of IL-1β and/or IL-4. After 24 hours of stimulation, the cell lysates were assayed for luciferase activity (see Materials and Methods). The data are expressed as fold increase over unstimulated cells. The results represent the mean ± SEM of three experiments. ^*P < .05 in comparison with cells cultured in the presence of IL-1β alone.