Calpain 2 also known as CAPN2 is a crucial intracellular calcium-dependent cysteine protease, plays a significant role in the regulation of cellular processes by cleaving cytoskeletal and submembranous proteins, which is essential for cytoskeletal reorganization and muscle protein degradation. Calpain 2 is primarily located in the cytoplasm and is activated by calcium ions, highlighting its importance in cellular signaling pathways and muscle function. Calpain 2 exists as a heterodimer, consisting of a small regulatory subunit and one of three large catalytic subunits, which include Calpain 1, Calpain 2, and Calpain p94. Calpain activity is tightly regulated by calpastatin, which inhibits both proteolytic activity and membrane binding, with calpastatin existing in tissue and erythrocyte types due to alternative splicing and proteolytic processing.