Myofibrillar proteins treated by protein kinase A and alkaline phosphatase were degraded by μ-calpain.
Degradation of myosin heavy chain, actin, desmin and troponin T was analysed.
Phosphorylation prevents myofibrillar proteins degradation by μ-calpain.
Dephosphorylation enhances myofibrillar proteins degradation by μ-calpain.