CLU and cancer: We further identified 57 glycoproteins with more than 2 significantly different site-specific glycoforms at one specific glycosite between drug-sensitive and resistant cell lines, and found that more than half of them had been demonstrated to be involved in chemoresistance of various cancer types, among which the key roles of AXL, L1CAM, TIMP1 and Clusterin in MDR were massively studied.