RLC phosphorylation does not alter viscoelastic stiffness under relaxed conditions (pCa 8.0). (A–D) Elastic moduli (A and B) and viscous moduli (C and D) values plotted against frequency for AP and MLCK treated strips from WT and cMyBP-C KO mice (mean ± SEM). The number of biological and technical replicates is listed in Table 1.