To remove eventual
residual DNA, the RNA was treated by DNase (Sinaclon Bioscience, Tehran, Iran);
the RNA was then measured and qualified by spectrophotometry. Only RNA with
an absorbance ratio (A260/A280) of >1.9 was used for synthesis of cDNA. Total
RNA was reverse transcribed into cDNA using PrimeScript™ RT Reagent Kit
(Takara Bio Inc., Japan). The reverse transcription mix was heated to 85°C for 5 s to
inactivate reverse transcriptase and denature the RNA and then stored at -20°C.