Mass spectrometric acidic N-glycan profile of hESC. A. MALDI-TOF MS spectrum of acidic N-glycan fraction isolated from a hESC sample. B. Average of relative signal intensities from 40 most abundant sialylated N-glycans of the four hESC lines, EBs, and stage 3 differentiated cells. N-glycan signals carrying structural features associated with either hESC (F ≥ 2, red circles) or differentiated cells (N = H, gray circles) are indicated below panel B. See the legend of Figure 1 for details and monosaccharide symbols.