The effect of the D166V mutation on RLC phosphorylation in transgenic mouse ventricular myofibrils blotted with +P-human RLC antibody recognizing phosphorylated human RLC (transgenic). Lane 1, +P WT st, phosphorylated recombinant standard WT protein; lane 2, Tg-WT RV, transgenic wild type myofibrils isolated from right ventricles of Tg-WT mice; lane 3, Tg-D166V RV, transgenic D166V mutant myofibrils isolated from right ventricles of Tg-D166V mice; D166V st, non-phosphorylated recombinant human D166V standard protein. Myosin essential light chain (ELC) served as a loading control and was detected with monoclonal MAB150 antibody.