Fig. 2. Stable expression of Snail induces MMP-9 promoter activity and is relieved by siSnail. (A) Schematic representation of the MMP-9 promoter and the deletion mutant constructs (I-VI), indicating the position of potential regulatory control elements. (B) Diagram showing the increase in activity of the different constructs transiently expressed in MDCK-CMV cells (white bars) or MDCK-Snail cells (black bars). Luciferase and renilla activities of each promoter construct are relative to that obtained with the pGL2 control plasmid, expressed as the mean±s.d. of three independent experiments. (C) Induction of MMP-9 promoter mediated by Snail is relieved by siSnail. Analysis of -1170 MMP-9 promoter activity (construct I) in control (MDCK-CMV, MDCK-Snail) and in the indicated individual clones obtained after stable transfection of Snail siRNA. Promoter activity was determined as in B. Results represent the mean±s.d. of four independent experiments.