ProcessingO-glycan core 1, Gal?1-3GalNAc?-R. Specificities of core 2, UDP-GlcNAc: Gal?1-3GalNAc-R(GlcNAc to GalNAc) ?6-N-acetylglucosaminyltransferase and CMP-sialic acid:Gal?1-3GalNAc-R ?3-sialyltransferase | doi.page