The IL-6 Leeporter™ Luciferase Reporter cell line is a stably transfected NIH 3T3 cell line which expresses Renilla luciferase reporter gene under the transcriptional control of the IL-6 promoter. As a pleiotropic cytokine, interleukin 6 (IL-6) has pro- and anti-inflammatory roles which is not only involved in normal functions of the immune system, hematopoiesis and  metabolism but also involved in the pathogenesis of metabolic and cardiovascular diseases. IL-6 gene induction is generally regulated by several transcription factors that activate the consensus sequences in the IL-6 promoter region, which include AP-1, C/EBP-beta and NF-kB in response to various proinflammatory cytokines, growth factors, and pathogen-associated molecular patterns such as Toll-like receptor (TLR) ligands. The IL-6 induction by lipopolysaccharide (LPS), the TLR4 ligand as well as by a proinflammatory cytokine, IL-6, is shown in Figures 1 and 2.