Localization of transcription enhancer activity of the EH subfragment in HA-1 cells.

The indicated fragments of EH were subcloned into the vector pMHO1CATΔ-33, which contains a minimal HO-1 promoter (−33 to +73). E indicates EcoRI; A, AflII; B, BsrBI; T, TaqI; R, RsaI; H,HindIII. HA-1 cells were transiently transfected with the indicated CAT constructs and incubated with 10 μM ZnPP or 100 μM ZnCl₂ for 24 hours. The CAT assay was carried out as described under “Materials and methods.” The data represent the average value from 3 independent experiments and the mean fold induction of CAT activity in extracts of cells incubated with ZnPP or ZnCl₂ compared to that in extracts of cells incubated with the constructs alone.