Fig. 4.

Cellular Sp1 and Sp3 protein levels, a comparison of transcriptional activity bound to the consensus Sp1 site between Caco-2 and DLD-1, and a SL2 cell transfection experiment.

Cellular Sp1 and Sp3 proteins of various cell lines are shown. Long and short forms of Sp3 proteins are marked. (b) In the upper part, constructs of TransLucent vectors (Panomics Co.) with or without consensus Sp1 motifs are illustrated. With these vectors, the total transcriptional activities whose target was the consensus Sp1 motif were analyzed using Caco-2 and DLD-1 cells, respectively. Cell culture was performed in triplicate, and statistical significance was calculated by Student t test. *** denotes p<0.005. (c) Effects of Sp1 and Sp3 overexpression on PLD1 promoter activity. SL2 cells lacking Sp family proteins were cultured in triplicate. Luciferase vectors of –154 bp PLD1/Luc and pPac-RL (as a control of transfection efficiency) were transfected together with either pPac-Sp1 or pPac-USp3 expression vector as described in the Materials and Methods. The relative luciferase activity of each sample was calculated as –154 bp PLD1/Luc /pPac-RL. Statistical significance is shown. ** means p<0.01 and *** denotes p<0.005.