OGA and breast neoplasm: Primary breast tumor tissues showed an increased O-GlcNAcase and lysosomal hexosaminidase activity than the corresponding adjacent normal samples, with a significantly decreased O-GlcNAc mono-glycosylation.275 The enzyme activity of O-GlcNAcase was also increased in thyroid cancers and the modified proteins showed a predominantly nuclear distribution.276 This situation is different in other studies.