O.D. data linearity is protein dependent. Pooled pregnant human myometrial tissue homogenates extracted in an SDS-based lysis buffer were run in 2-fold serial dilutions from 40 μg to 160 ng of lysate. The following proteins were detected (left to right from top to bottom): MYPT1, ERK1/2, MLC-20, ROCK1, αSMA, HSP27, αActinin, GAPDH, and Cofilin. Each protein was detected with infrared fluorescence (top figure in each panel) and chemiluminescence (bottom figure in each panel). 2 independently prepared membranes were analysed with each detection method.