The relative expression level of mRNAs was determined by real-time RT–PCR and was estimated using the ΔCt value. ΔCt value
was calculated using Ct (cycle threshold) values in each gene and GAPDH (ΔCt value=Ct value of each gene - Ct value of GAPDH).
If the ΔCt value is lower, the relative RNA level is higher. Results are expressed as the mean ± SD (n=6).