Source: Human Cells. MW :36.4kD. Recombinant Mouse Cathepsin B is produced by our Mammalian expression system and the target gene encoding His18-Phe339 is expressed with a 6His tag at the C-terminus. Cathepsin B (CatB) is an enzymatic protein belonging to the peptidase (or protease) families. which is believed to participate in intracellular degradation and turnover of proteins. Has also been implicated in tumor invasion and metastasis.