The major eukaryotic mRNA decay pathway occurs through deadenylation, decapping, and 5' to 3' degradation of the mRNA. Decapping is a critical control point in this decay pathway. Edc4 (enhancer of mRNA decapping 4), also known as human enhancer of decapping large subunit (HEDLS), RCD-8 or Ge-1, is a 1,401 amino acid protein belonging to the WD repeat EDC4 family that is involved in mRNA decapping during mRNA degradation. As part of the mRNA degradation process, Edc4 becomes part of a complex that also contains hDcp1a, hDcp2a, RCK and Edc3. Localizing to P-body and cytoplasm, Edc4 contains a nuclear localization sequence (NLS) which enables it to selectively enter the nucleus as well. Edc4 becomes phosphorylated upon DNA damage and exists as two alternatively spliced isoforms that are encoded by a gene that maps to human chromosome 16q22.1.