For each MS/MS method, core 3 glycans were the most dominant structure identified, outnumbering core 1 and core 2 glycans as well as simple GalNAc glycans. The site that showed the most microheterogeneity was S253, for which EThcD identified 9 different glycan compositions, followed by S171 with 8 glycan structures EThcD (Figure ). For these same two sites, UVPD identified 6 glycan compositions for S253 and 7 for S171, while HCD identified 3 glycan compositions for S253 and 6 for S171.