On the use of ratio standard curves to accurately quantitate relative changes in protein levels by Western blot

The use of a ratio standard curve in measuring relative changes in protein levels by directly forming the ratio of the densitometric values of bands on a Western blot was examined. The ratio of densitometric measurements was plotted against known amount ratios of the protein examined to obtain this curve. A ratio standard curve was plotted to accurately determine relative changes in lamin C protein expression in U-373 MG cells treated with lamin siRNA. The error in forming the ratio between the densitometric values of bands on Western blots to determine relative changes can be avoided using a standard curve to determine the actual amounts of that protein in control and experimental samples. This simple method should prove to be useful in laboratories routinely determining relative changes in protein levels by densitometry of Western blots.