The RNA samples were reversely transcribed into cDNAs. In brief, 5 L RNA mixed with 5 L dNTP (2.5 mM) and 1 L oligod(T)15 was incubated for 5 min at 65 ◦C. The resulting mixture was cooled immediately, placed in 5 L M-MLV 5×reaction buffer, 1 L cloned ribonuclease inhibitor, 1 L M-MLV reverse transcriptase, and RNase-free ddH2O to a final volume of 25 L, mixed gently,and then incubated at 37 ◦C for 1 h. The reaction was completed at70 ◦C for 15 min. The cDNA products were stored at−20 ◦C.