Conversely, O-GlcNAcylation could protect MCF-7 breast cancer cells against DOX by stabilizing box C/D small nucleolar ribonucleoprotein complexes (snoRNPs) core component fibrillarin (FBL) on Ser142 and maintaining ribosomal RNA methylation and ribosome assembly (110) (Figure 2). Here, FBL is linked to breast cancer.