The RQ-RT-PCR product obtained from the hOCT1 TaqMan Gene Expression Assay (Hs00427552_m1; Applied Biosystems Inc, Foster City, USA) was purified using the QIAquick PCR Purification Kit (Qiagen, Hilden, Germany) and ligated into pCR 2.1 vector using the TA Cloning Kit (Invitrogen, Carlsbad, USA). Recombinant plasmids were subsequently used for Escherichia coli transformation. Plasmid DNA was isolated using the QIAprep Spin Miniprep Kit (Qiagen, Hilden, Germany) and used as the standard for hOCT1 absolute copy number quantification in 10-fold dilutions (range 10 6-10 1 copies). Standards for GUS, BCR/ABL, and ABL with serial numbers CGRS-03, FGRS-10, and CGRS-01, respectively (FusionQuant 1 Standards Kit, Ipsogen, Marseille, France), were used for the absolute quantification of these particular genes. 