CAPN7 (calpain 7) is a unique calcium-regulated cysteine protease that differs from other calpains by containing two tandem MIT (microtubule-interacting and trafficking) domains instead of the typical penta-EF-hand domain 1. CAPN7 functions as a critical regulator of multiple cellular processes through its proteolytic activity. In membrane trafficking, CAPN7 facilitates EGFR degradation via the endosomal sorting pathway by interacting with ESCRT-III proteins, particularly IST1, through its MIT domains 2. During cytokinesis, CAPN7 is recruited to midbodies through IST1 binding and is essential for efficient abscission and NoCut checkpoint maintenance 34. In reproductive biology, CAPN7 negatively regulates endometrial function by degrading key transcription factors: it cleaves HOXA10 through a PEST sequence-mediated mechanism, impairing embryo implantation 5, and hydrolyzes AKT1 to promote FoxO1 nuclear exclusion, disrupting decidualization 6. CAPN7 is also involved in protein degradation disorders, as it contributes to SMN protein degradation in spinal muscular atrophy, making cysteine protease inhibitors potential therapeutic targets 7. These findings establish CAPN7 as a multifunctional protease with significant roles in cellular division, membrane trafficking, and reproductive health.