Cytokines and growth factors play a crucial role in both kidney development and progression of renal diseases. Elevated levels of several cytokines have been identified in the urine and renal biopsy specimens of patients with glomerulonephritis, and the development of kidney pathology is a common event in transgenic mice overexpressing some cytokine genes. Cytokines/growth factors have been shown to produce a wide range of biochemical effects in cultured renal cells including regulation of gene expression, however, the precise mechanisms by which this occurs is unclear. We have investigated the regulation of transcription factor gene expression in renal mesangial cells by bacterial endotoxin, cytokines (IL-1, IL-6, TNFot, INF-y) and the growth factor PDGF. In particular we have examined the regulation of transcription factors from the API and C/EBP families, which are intimately linked with kidney development and disease Using the techniques of northern blot analysis and reverse-transcription polymerase chain reaction (RT-PCR) we have demonstrated that API isoforms (c-fos, cjun, junB) are upregulated after 30 minutes and show the same expression pattern regardless of the mediator used. Whereas the C/EBP isoforms (a, β, and 6) show differential regulatory patterns depending on the mediator used with changes in expression occurring after 3-6 hours. We acknowledge research support from Wejbome and BBSRC.