Total RNA was extracted using QIA amp RNA extraction kit provided from QIAGEN worldwide companies. The concentration and purity of RNA were determined by measuring its absorbance at 260 nm (A 260 ) and 280 nm (A280) in a UV visible spectrophotometer. Total RNA (2 μg) was reversetranscribed to cDNA with High-Capacity cDNA Archive kit provided from Applied Biosystems. cDNAs were stored at -20°C until real-time quantitative PCR was performed.