In DND41, KOPTK1 and TALL-1 cells, short term exposures to compound 8 arrested G1/S cell-cycle progression further supported by the reduction of Cyclin D3 and CDK4 levels, both known to be regulated by Notch signaling to promote transition through the cell cycle during T-ALL leukemogenesis41. The gene discussed is CDK4; the disease is acute lymphoblastic leukemia.