Role of Klf4 in Cox-2 expression. (A) Semi-quantitative RT-PCR of Cox-2 mRNA indicates a significant decrease in Si+LPS cells compared to LPS-treated cells (B) Immunoblot for Cox-2 in total protein isolates from BV-2 cells. The protein levels of Cox-2 were also found to be significantly reduced within 12 h of LPS treatment in Si+LPS cells compared to LPS-treated cells. The graphs represent relative Cox-2 mRNA and protein levels with respect to the control samples. (C) Luciferase assay for Cox-2 promoter activity using a pCOX301/pGL2 construct. This construct has the luciferase gene directly regulated by Cox-2 promoter. There is a significant reduction in luciferase activity in the Si+LPS condition compared to the LPS-alone condition, indicating that Klf4 may be involved in regulating Cox-2 promoter activity. *, **, Statistical differences in comparison to control values and #, Statistical differences in comparison to LPS-treated values. (* p < 0.05, ** p < 0.01, # p < 0.01).