PPIB and central nervous system cancer: Cathepsin B, an intracellular protease anda lysosomal enzyme, has been reported tobe associated with malignant behavior ofseveral human tumors including colon, breast,prostate, bladder cancer and also glioma (18).One of the initial studies evaluating the role ofcathepsin B in glioma progression and invasionwas performed by Rempel et al. (19) usingseveral methods (e.g. immune histochemicalstaining, enzyme activity assays and northernblot analysis) they showed that cathepsin Boverexpression is associated with more invasivenature in glioma tumors.