Important functional domains in dermatan or dermatan sulfate (DS) are generated by the action of an epimerase (which converts D-glucuronic acid into its epimer L-iduronic acid) together with 4-O-sulfation. These domains are named 4-O-sulfated iduronic acid blocks (Pachebo et al. 2009). Carbohydrate sulfotransferase 14 (CHST14) (Evers et al. 2001) mediates the transfer of sulfate to position 4 of another N-acetylgalactosamine (GalNAc) residue of D2,4(S)2-PG (sulfated on position 2 of IdoA and position 4 of GalNAc) to produce a further sulfated product D2,4,4(S)3-PG (sulfated on another GalNAc in addition to the ones above).