The G-CSF factor stem-loop destabilising element (SLDE) is an RNA element secreted by fibroblasts and endothelial cells in response to the inflammatory mediators interleukin-1 (IL-1) and tumour necrosis factor alpha and by activated macrophages. The synthesis of G-CSF is regulated both transcriptionally and through control of mRNA stability. In unstimulated cells G-CSF mRNA is unstable but becomes stabilised in response to IL-1 or tumour necrosis factor alpha, and also in the case of monocytes and macrophages, in response to lipopolysaccharide. It is likely that the presence of the SLDE in the G-CSF mRNA contributes to the specificity of regulation of G-CSF mRNA and enhances the rate of shortening of the poly(A) tail.^[1]