Ezh2-driven transcriptional activation requires CDK1-mediated phosphorylation. (A) FACS analysis of phospho-EZH2 (T487) in MYCN-driven TCL spleen cells treated ex vivo with DMSO or Ro-3306 (CDK1 inhibitor) for 8 hours. (B) Normalized expression levels of Cdk1 in CD4 T cells and in MYCN-driven lymphoma cells. (C) Representative ChIP-seq tracks for the Cdk1 promoter showing binding of MYCN, Ezh2, Suz12, p300, and histone marks H3K4me3, H3K27ac, and H3K27me3 in MYCN-driven TCL. (D) Normalized counts for CDK1 from the PTCL cases from the Leuven cohort and the Kyoto cohort. Stars indicate patients with MYCN overexpression. (E) FACS analysis of phospho-EZH2 (T487) in RPMI-8402 cells treated for 16 hours with CDK1 inhibitors Ro-3306 or BMS-265246. (F) FACS analysis of EZH2 or MYCN in MYCN-driven TCL spleen cells treated ex vivo with DMSO or Ro-3306 for 8 hours. (G) qRT-PCR analysis of MYCN and EZH2 target gene expression in MYCN-driven TCL cells treated ex vivo for 8 hours with 4 μM Ro-3306. Data are represented as mean ± standard deviation. (H) qRT-PCR analysis of MYCN and EZH2 target gene expression in RPMI-8402 cells treated for 36 hours with Ro-3306 or BMS-265246. (I) Twenty-four- and 48-hour ex vivo treatment of MYCN-driven TCL spleen cells with 2 μM of the CDK1 inhibitors Ro-3306 or BMS-265246. (J) Sixty-hour treatment of RPMI-8402 cells with CDK1 inhibitors Ro-3306 and BMS-265246. ∗∗∗∗P < .0001, ∗∗∗P < .001, ∗∗P < .01, ∗P < .05.