Used in research settings to quantify levels of Calpastatin (CAST), the endogenous inhibitor of calpain proteases, in biological samples such as cell lysates, tissue homogenates, and serum. This ELISA kit enables investigators to study the regulation of calpain activity in cellular processes including apoptosis, muscle degradation, neurodegeneration, and ischemia-reperfusion injury. It is particularly valuable in neuroscience, cancer, and muscular disorder research where imbalances in the calpain-calpastatin system are implicated. The assay provides a reliable, sensitive, and high-throughput method to monitor CAST concentration, supporting both basic science and preclinical studies focused on protease regulation pathways.