methods and any associated references are available in the online version of the paper at http://www.nature.com / naturemedicine/.
 t - cell acute lymphoblastic leukemia ( t - all ) is an immature hematopoietic malignancy driven mainly by oncogenic activation of notch1 signaling1 . in this study 
 we report the presence of loss - of - function mutations and deletions of ezh2 and suz12 genes , encoding critical components of the polycomb repressive complex 2 ( prc2 ) complex2,3 , in 25% of t - alls . to further study the role of the prc2 complex in t - all , we used notch1-induced animal models of the disease , as well as human t - all samples , and combined locus - specific and global analysis of notch1-driven epigenetic changes . 
 these studies demonstrated that activation of notch1 specifically induces loss of the repressive mark lysine-27 tri - methylation of histone 3 ( h3k27me3)4 by antagonizing the activity of the polycomb repressive complex 2 ( prc2 ) complex . 
 these studies demonstrate a tumor suppressor role for the prc2 complex in human leukemia and suggest a hitherto unrecognized dynamic interplay between oncogenic notch1 and prc2 function for the regulation of gene expression and cell transformation . 
Methods
Supplementary Material