45M1 antibody recognizes stomach mucus preferentially by Western blot, and ELISA.a) Immunohistochemistry. The 45M1 antibody (diluted 1:100) does not recognize the majority of the cells lining a section of fetal mouse small intestine. Magnification using 40× objective. b) Western blot hybridized with the C4 antibody. 23.4 μg of mucus collected from either guinea pig small intestine (I) or stomach (S) was subjected to electrophoresis through a 1.0% agarose gel and then transferred to a nitrocellulose membrane. Hybridization with the 45M1 antibody labeled high molecular weight protein in stomach mucus, with no labeling evident for small intestinal mucus. Western blot shown is representative of three separate blots. c) ELISA wells were coated with 5.8 μg of guinea pig stomach or small intestinal mucus. 45M1 (1:100 and 1:1000) recognized stomach mucus, but not small intestinal mucus. Each sample was assayed in triplicate and data are shown as mean ± SEM. The assay was done twice using two independent sample isolations, with similar results obtained each time.