Pou5f1 is modified by O-GlcNAc in human embryonic stem cells. Western blot of protein immunoprecipitated by an anti-Pou5f1 antibody. The RL2 antibody recognizes a 43 KDa, O-GlcNAc modified protein that is immunoprecipitated from the nucleocytosolic fraction of human ES cells (line BG02) by an anti-Pou5f1 antibody. The immunoprecipitation was specific, since the nucleocytosolic fraction was precleared with a mixture of IgG and A/G PLUS agarose prior to incubation with the anti-Pou5f1 antibody. The anti-Pou5f1 antibody recognizes the same band when the blot is stripped and reprobed, confirming that Pou5f1 protein is modified by O-GlcNAc.