RNA-binding proteins (RBPsIn mammalian cells, RNA-binding proteins (RBPs) are major regulators of mRNA stability and translation. Some RBPs associate with RNA sequences that are widely present in mRNAs, such as the 5Ј cap structure (7-methyl-guanosine) or the 3Ј poly(A) tail. However, a distinct, albeit heterogeneous, group of mammalian RBPs associate with specific mRNA sequences (cis elements) frequently present in the 5Ј and 3Ј untranslated regions (UTRs) and effect changes in mRNA stability and translation rates (16,46,54). Traditionally, these mRNA stability and translation determinants have been termed AU-rich elements (AREs) because several early examples of stability sequences were prominently AU rich and often included the pentamer AUUUA (13,48,59). However, with growing numbers of mRNA stability and translation determinants elucidated over the past decade, many examples of regulatory sequences have been described which lack AUUUA pentamers and do not exhibit a particular AU richness (15,30,38,40,41,61,64). Thus, while the term "ARE-RBP" is deeply ingrained in the literature of RBPs implicated in stabilizing/ destabilizing mRNAs and in promoting/suppressing translation, we propose the alternative nomenclature TTR-RBPs (for turnover and/or translation regulatory RBPs) to refer to this subset of RBPs.