The IL-1/TNF response element of the ACT gene confers responsiveness to IL-1 and TNF onto other promoters. The IL-1/TNF response element was cloned in front of the SPI-3, TIMP-1, andtk promoters. Human astrocytes were transfected with ptkCATΔEH, pSPI-3 (-148)CAT, prT-61, p(IL-1enh)CAT, pSPI-3(IL-1enh)TCAT, pTIMP-1(IL-1enh)CAT, or p2x(IL-1enh)CAT, and β-galactosidase expression vector as an internal control for transfection efficiency. One day after transfection, cells were stimulated with indicated cytokines, cultured for another 24 hr, and harvested. CAT activities were normalized to β-galactosidase activities (cpm/unit × 10−3).