Mammalian tumour necrosis factor-α (TNF) and granulocyte/macrophage colony-stimulating factor (GM-CSF) AU-rich elements (AREs). (a) The central ARE region of the TNF mRNA 3' untranslated region from all mammalian species for which this region of the mRNA has been deposited in GenBank. In most cases these were derived from EST sequences; note that the horse sequence has not been completed at the 3' end. The overlines indicate the nine-base tristetraprolin (TTP)-binding site 5'-UUAUUUAUU-3'. Sequences from the various mammals are divided into groups based on the pattern of these nonamers, with the top group of 10 mammals being the most common group. (b) A similar approach was used to align the central ARE from the GM-CSF transcript, after alignment using the program ClustalW. The asterisks below the alignment represent base identity at that position; note that gaps were used to optimize the alignment. The overlines again represent the nonamer TTP-binding site. These data are modified from .