Updated project metadata. Being the most malignant disease among females, breast cancer has morbidity and mortality in the first and second positions among various cancers [1]. Up to now, chemotherapy has been the most common therapy [2]; however, multidrug resistance (MDR) often occurs to give low overall survival rate. Thus, it is urgent to figure out the mechanism of chemotherapy resistance. The first step of drugs to attack tumor cells is to interact with the plasma membrane, and solute carrier (SLC) family proteins are uptake transporters [3]. On the other side, the efflux transporters (such as ATP-binding cassette, ABC) pump drug out of cancer cells [4]. The main mechanism of MDR is the upregulation of ATP-binding cassette (ABC) transporters [5]. Breast cancer resistance protein (ABCG2), multidrug resistance protein (ABCC1) and P-glycoprotein (P-gp) have been extensively studied [6,7]. Formation of CSCs [8], DNA damage [9] and cell apoptosis [10] and epithelial mesenchymal transition (EMT) are other mechanisms of MDR. To zoom in on the correlation between altered glycosylation and drug resistance and to find out the putative biomarkers, MS-based glycoprotomics is a method of choice. Here, we report our N-glycoproteomics study of differential N-glycosylation from the whole cell lysate of MCF-7/ADR CSCs (adriamycin-resistant MCF-7 CSCs) relative to MCF-7 CSCs. Intact N-glycopeptides from both cells were enriched with ZIC-HILIC, isotopically diethylated, mixed with 1:1 ratio, and the mixture was analyzed by C18-RPLC-ESI-MS/MS (HCD with stepped NCE). Differentially expressed N-glycopeptides (DEGPs) were identified and quantified with database search using GPSeeker.