Calpeptin is widely used in research settings to inhibit calpain, a family of calcium-dependent proteases involved in cellular processes such as apoptosis, signal transduction, and cytoskeletal remodeling. By blocking calpain activity, calpeptin helps in studying the role of these enzymes in neurodegenerative diseases, ischemia-reperfusion injury, and muscle degradation. It is also employed in cell culture experiments to prevent protein degradation and maintain cell viability during stress conditions. Due to its cell-permeable nature, calpeptin is effective in both in vitro and ex vivo models, making it a valuable tool in mechanistic studies of calpain-mediated pathways.