Real-Time RT-PCR quantification of β-actin mRNA. Standard curve showing amplification efficiencies of ten-fold serial dilutions of the pBactin-231 template. Real-Time PCR amplifications were performed using β-actin specific primers BA67 and BA68. The calculated Ct values were plotted versus the log of the initial amount of pBactin-231 molecules (104 to 109) to generate the standard curve. Squares and circles represent β-actin standards and mRNA samples, respectively.