As shown in Fig. 1a, compared to cells transduced with non-silencing control shRNAs (sh0 and sh0G), construct sh491 resulted in 90% reduction in HPRT mRNA in human acute myeloid leukemia Molm13 cells as determined by real-time RT-PCR, while that of sh50 was only 50%. This evidence concerns the gene HPRT1 and acute myeloid leukemia.