In embryonic stem (ES) cells, plays a crucial role in the differentiation potential, particularly along the neural lineage, regulating gene induction and H3 'Lys-4' methylation at key developmental loci, including that mediated by retinoic acid (By similarity).Does not affect ES cell self-renewal (By similarity).Component or associated component of some histone methyltransferase complexes which regulates transcription through recruitment of those complexes to gene promoters.