MS analysis of HL-60 N- and O-glycans. MALDI-TOF MS and TOF-TOF MS/MS spectra of permethylated N-glycans of the zoomed scan m/z 3140 to 3147 molecular ion cluster of (A) WT, (B) ST3Gal-4⁻ HL-60s (knockdowns), (C) CRISPR/Cas9 ST3Gal-4-KO HL-60 cells. Panels Ai, Bi, Ci depict the zoomed scan area; panels Aii, Bii, Cii depict the MALDI TOF-TOF MS/MS of the corresponding molecular ion cluster. (D) Partial MALDI-TOF MS spectra of permethylated O-glycans derived from the WT (i), ST3Gal-4⁻ knockdown (ii), and ST3Gal-4-KO (iii) HL-60 cells. All spectra of N- and O-glycans were derived from the 50% MeCN fraction. All molecular ions are [M+Na]⁺. For the MS/MS panels, arrows indicate the losses indicated from the molecular ion. Putative structures are based on composition, tandem MS, and biosynthetic knowledge. Full MALDI-TOF MS spectra of the N- and O-glycans can be found in supplemental Figures 3 and 4.