The calpain-3 (CAPN3) antibody is a crucial tool for studying the CAPN3 protein, a calcium-dependent protease predominantly expressed in skeletal muscle. CAPN3 plays a vital role in muscle homeostasis, regulating processes like sarcomere remodeling, apoptosis, and signal transduction. Mutations in the CAPN3 gene cause limb-girdle muscular dystrophy type 2A (LGMD2A), a progressive disorder characterized by muscle weakness and atrophy. Researchers use CAPN3 antibodies in Western blotting, immunohistochemistry, and immunofluorescence to assess protein expression, localization, and stability in muscle tissues. These antibodies help identify CAPN3 deficiency or abnormal processing, aiding LGMD2A diagnosis. However, interpreting results requires caution, as secondary protein degradation in muscle biopsies may lead to false negatives. CAPN3 antibodies also contribute to exploring the protein's interaction with partners like titin and dysferlin, shedding light on disease mechanisms. Recent studies focus on CAPN3's dual roles in muscle regeneration and pathology, with therapeutic strategies targeting gene correction or calpain inhibition under investigation. Despite challenges in antibody specificity and assay standardization, CAPN3 remains a key biomarker and research target in neuromuscular disorders.