Mass spectrometric neutral N-glycan profile of human embryonic stem cells (hESC). A. MALDI-TOF MS spectrum of neutral N-glycan fraction isolated from a hESC sample. B. Average of relative signal intensities from 40 most abundant neutral N-glycans of four finnish hESC lines (blue columns), embryoid bodies derived from the hESC lines (EB, red columns), and stage 3 differentiated cells (st.3, white columns). The columns indicate the mean abundance of each glycan signal (% of the total detected glycan signals). Error bars represent the standard error of mean. Proposed monosaccharide compositions are indicated on the x-axis and proposed structures for the major N-glycans are shown as schematic drawings. Gray circle/H: hexose, green circle: mannose, yellow circle: galactose, blue circle: glucose, gray square/N: N-acetylhexosamine, blue square: N-acetylglucosamine, red triangle/F: fucose/deoxyhexose, violet diamond/S: N-acetylneuraminic acid, light blue diamond/G: N-glycolylneuraminic acid. Asterisks indicate known polyhexose contamination that was not included in panel B.