Transcriptional activation of CDK6 by MLL-AF9. (A) Schematic of the regions in MLL-AF9 and AF9 targeted by the shRNAs used in panels B and C. (B) Expression of HOXA9, CDK6, and CDK4 mRNA in THP-1 cells after MLL-AF9 suppression. (C) Expression of CDK6 protein in THP-1 cells after MLL-AF9 suppression. (D) Expression over time of MLL-AF9 and CDK6 in K562 cells transduced with MLL-AF9. (E) Expression of CDK6 in HL-60 cells, normal human CD34^pos cells, and murine Ba/F3 cells transduced with MLL-AF9. (F) ChIP-seq analysis identifying Cdk6 as direct MLL-AF9 target gene in mouse BM cells transformed with MLL-AF9. The top track is derived from cells before injection into recipient mice; the bottom track is derived from a fully developed mouse leukemia.