We used a metabolic labeling (GalNAz) based O-GlcNAc sites identification and quantification proteomics method to compare the O-GlcNAc chromatin of MCF-7 and MCF-7/ADR cells. The O-GlcNAc chromatin-associated proteins can be metabolically labeled with azides, followed by reaction with a cleavable DADPS (dialkoxydiphenylsilane) alkyne-biotin linker and enrichment with streptavidin beads. After cleavage of DADPS by formic acid, O-GlcNAc modified peptides were quantitative analysis using tandem mass spectroscopy (MS).