Effect of GKLF on the transcriptional activity of mutated CD1 and heterologous reporters plasmids. –163Sp1mutLuc, mutation of the Sp1 sequence within the context of the –163 bp fragment of the CD1 promoter; –163E2FmutLuc, mutation of the E2F sequence in the context of the –163 bp of the CD1 promoter; CD1(Sp1)Luc, heterologous reporter construct consisting of the CD1 Sp1 sequence; and CD1(E2F)Luc, heterologous reporter construct consisting of the CD1 E2F. Plasmids were cotransfected with sense GKLF (black bar) or pCDNA-3 (open bar) into L293 cells and luciferase activity was determined 48 h later. Data represent the mean ± S.E. of four separate experiments. *P < 0.05, compared to pCDNA-3-transfected cells in each individual construct.