Calcium-dependent cysteine protease that functions as a non- proteasomal, ubiquitin-directed protease regulating cell adhesion through cleavage of E-cadherin/CDH1. Binds to ubiquitinated proteins via its N-terminal, preferentially recognizing longer polyubiquitin chains including both 'Lys-48- and 'Lys-63'-linked chains. Recognizes the ubiquitinated E-cadherin-catenin complex and cleaves E-cadherin in a calcium- and ubiquitination-dependent manner resulting in lysosomal degradation of the resultant fragment (PubMed:41380969). Plays a critical role in eye, brain and cerebellar development (By similarity). In the developing brain, may regulate transcription factor abundance including PAX2 and PAX5 levels. Additional putative substrates include P-cadherin/CDH3, DCX and TUBB3 (By similarity). {ECO:0000250|UniProtKB:Q9JLG8, ECO:0000269|PubMed:32885237, ECO:0000269|PubMed:41380969}. This is the function of ENSG00000103326 (CAPN15, calpain 15).