PPIF and heart failure: Clear-cut evidence in support of CyPD as a master regulator of the PTP came from the observation that Ppif-/- mice show a striking desensitization to Ca2+ of the PTP [34], which provides substantial protection from cell death in a number of PTP-related paradigms, including ischemia-reperfusion injury [34], heart failure [35], and muscular dystrophies [36,37].