NGLY1 and melanoma: Although the quantities of peptides containing GlcNAc-asparagine that can be detected among the biological replicates of different cell samples appeared to vary, compared with control cells, melanoma cells with NGLY1 knockdown reproducibly showed higher contents of peptides containing GlcNAc-asparagine residues, indicating the functional defect of NGLY1 in the cells (Supplementary Figure S5D).