In vivo reporter gene assays. Firefly luciferase reporter gene constructs were designed to contain individual 5′-UTRs upstream of the luciferase reporter gene in the pGL3 vector (Promega). Rat L6 cells were transfected with either the host pGL3 vector (control) or the vector containing a specific PPAR- 5′-UTR. Cells were cotransfected with a plasmid expressing the Renilla luciferase enzyme. After 4 days, cell lysates were prepared and analyzed for firefly (hatched bars) and Renilla (solid bars) luciferase activities. The open bars show the ratio of firefly to Renilla luciferase (, values relative to control are , , , ).