Trypsin is a digestive enzyme commonly used in formalin-fixed, paraffin-embedded immunohistochemical procedures. Its digestive properties are in many cases required as a pretreatment, prior to the primary antibody application, to produce a signal with certain protein-antibody interactions. It is found more useful than boiling pretreatments for antibodies such as AE1/AE3. This product is provided in a ready-to-use (2 component) system.