Quantitative PCR products using a competitor template serving as an internal standard run on a 2% agarose gel. Equal amounts of sample RNA were reverse transcribed together with 0.04 ng (lane 1), 0.005 ng (lane 2), 0.001 ng (lane 3), 0.0005 ng (lane 4), and 0.0001 ng (lane 5) of wt1 standard cRNA and amplified by PCR. PCR products were quantitated after Southern blotting, and the equivalence point of sample RNA (851 bp) and standard RNA (706 bp) was determined by regression analysis as shown in the graph above.