Claudin1 belongs to the group of claudins. The claudins are components of tight junctions, which are specialized regions of cell to cell contact serving as a physical barrier to prevent solutes and water from passing freely through the paracellular space. This antibody is found in nearly all carcinomas. The staining there is much stronger than in normal tissues. In relation with EMA (positive), S-100 (negative) and GLUT1 it can be utilized as a robust marker in diagnosis of perineurioma and neurofibroma. Related with EMA, S-100 protein, CD34 and GFAP it may be helpful in the diagnosis of meningiomas from histologic mimics.