In T-ALL, MYB can be overexpressed by translocation or duplication[66, 67] and indeed five cell lines in our panel are known to carry extra chromosomal copies of MYB (ALLSIL, RPMI 8402,MOLT4, P12 Ichikawa, CCRF-CEM)[67]; however, these were not uniformly sensitive to CP-751,871 in our hands suggesting that multiple genetic variables likely contribute to the net pharmacological effect. This evidence concerns the gene MYB and acute lymphoblastic leukemia.