Western blot of murine brain and proximal colon tissue lysates. Immunoblotting was carried out as described in Methods. The protein standards used were phosphorylase, 94 kDa; bovine serum albumin, 67 kDa; ovalbumin, 43 kDa; carbonic anhydrase, 30 kDa; soybean trypsin inhibitor, 20 kDa; and lysozyme, 14 kDa. The immunoblot detected a 43 kDa band in colonic lysate.