Eukaryotic mRNA degradation is an essential aspect of gene regulation. Properly turning off transcript generation ensures that protein synthesis does not occur indefinitely. By ensuring that all mRNAs are destroyed, cells can adapt quickly to changing physiological and environmental conditions. Eukaryotic cytoplasmic mRNA degradation is predominately initiated by removal of the poly(A) tail at the 3′ end (deadenylation). Following deadenylation, either the mRNA is degraded in a 3′-5′ manner or the cap is removed and the mRNA is degraded 5′-3′ (reviewed in Coller and Parker, 2004). Determining mRNA decay rates, as indicated by mRNA half-life, is vital to understand how mRNA stability is modulated under various physiological conditions.