MYH14 and heart failure: Understanding how varying the level of isoform expression affects the twitch is important to understand why there are different levels of myosin expression across the heart and how alterations to myosin expression occur in heart failure and other pathologies—e.g., how much compensation can arise through a myosin isoform shift vs. changes in calcium transients or post-translational modifications of sarcomere proteins (phosphorylation, acetylation, etc.).