Figure 2.

Insulin-induced down-regulation of reporter gene expression mediated by the 5′ flanking and 5′-UTRs of the C/EBPα gene. Representative 3T3-L1 cell lines harboring either a 1,575-bp (□) or a 468-bp (▪) 5′ flanking/5′-UTR-luciferase construct were induced to differentiate as in Fig. 1. On day 9, differentiated adipocytes were exposed to 1 μg of insulin per ml, cell lysates were prepared, and luciferase assays were conducted at the times indicated. At 24 hours, other cell monolayers were washed once and then incubated with insulin-free medium. At the times indicated, cell lysates were prepared and luciferase assays were conducted.