Often, there is Ca2+ leakage from the RyRs in the SR, but this process is limited by calstabin-1. Calstabin-1 is a protein which has a high affinity for RyR, stimulated by the dystrophin. However, due to DMD mutations and thus reduction of dystrophin, the Calstabin-1 no longer binds with such a high affinity to the RyR, thus not blocking the calcium leakage