Figure 1

Scheme of pSUPER.retro vectors. pS−: original empty pSUPER.retro vector, with H1 promoter upstream ‘stuffer’ sequence; pSH1: pSUPER.retro vector in which shCOX-2 expression is controlled by H1 promoter; pSCOX−2: pSUPER.retro vector in which shCOX-2 expression is controlled by human Cox-2 promoter; pSTBE: pSUPER.retro vector in which shCOX-2 expression is controlled by a TBE-based promoter (carrying Tcf-binding elements).