For hOCT1 cDNA amplification, a TaqMan Gene Expression Assay (serial number Hs00427552_m1) (Applied Biosystems Inc, Foster City, USA) was used according to the manufacturer's recommendations. The final hOCT1 mRNA expression level was then calculated using the following formula: hOCT1 (absolute copies) /GUS (absolute copies) 3 100%. To detect the expression of the control gene GUS in all selected cell fractions, the primer set and probe from Beillard et al. were used [10] .