SKP2 and breast cancer: Caldwell et al. (Caldwell et al. 2010) showed that elevated O-GlcNAcylation and OGT promoted breast cancer cell growth and invasion, in part by regulating the oncogenic transcription factor forkhead box M1 (FOXM1) and multiple FOXM1-specific targets, such as s-phase kinase-associated protein 2 (SKP2) and cyclin-dependent protein kinase inhibitor (P27Kip1).