An homogeneous quantity (0.8-1 mg) of the RNA samples was subjected to a reverse transcription step using the highcapacity cDNA archive kit (Applied Biosystems, USA) as described by the manufacturer. Single-stranded cDNA products were then analyzed by real-time PCR using the TaqMan Gene Expression Assays according to the manufacturer's instructions (Applied Biosystems, USA). Single-stranded cDNA products were analyzed using the ABI PRISM 7700 Sequence Detector (Applied Biosystems, USA). The efficiency and reproducibility of the reverse transcription were tested using 18S rRNA TaqMan probes. Five assays were used, GAPDH-5 0 (Hs99999905_m1), GUSB-5 0 (Hs00388632_gH), GUSB-3 0 (Hs99999908_m1), TFRC-5 0 (Hs00951086_m1) and TFRC-3 0 (Hs00951085_m1). In each case, duplicate threshold cycle (Ct) values were obtained and averaged; then expression levels were evaluated by a relative quantification method (27) .