GAPDH mRNA expression. The Ct value showed the expression level of GAPDH was constant (within the acceptable range of 13-16) for the total RNA concentration in the range of 50-100 ng/μl (A). The melting curve demonstrated all PCR products had the specific melting temperature at 87°C (B). Agarose gel electrophoresis confirmed the size of all the PCR products generated was at 217 bp (C). The standard curve showed the threshold cycle (Ct) versus concentration of the total RNA from serial dilution (D).