Mouse Legumain,also known as LGMN, is a cysteine protease belonging to peptidase family C13 and is expressed in kidney and placenta abundantly. LGMN has a strict specificity for hydrolysis of asparaginyl bonds. It can also cleave aspartyl bonds slowly, especially under acidic conditions. The mammalian legumain is involved in the processing of proteins for MHC class II antigen presentation in the lysosomal/endosomal system. It plays a role in the regulation of cell proliferation via its role in EGFR degradation. Legumain deficiency causes the accumulation of pro-Cathepsins B, H and L, another group of lysosomal cysteine proteases. Overexpression of Legumain in tumors is significant for invasion/metastasis. Mammalian legumain is inhibited by iodoacetamide and maleimides. Legumain activation appears to be autocatalytic and can be triggered by acidic pH.