Fig. S1.

Breeding strategy and characterization of IEC-Cosmc mice. (A) Breeding strategy: Vil-Cre⁺ males were bred to Cosmc^f/+ females to generate intestinal epithelia-specific KO (Vil-Cre⁺;Cosmc^f/y), mosaic (Vil-Cre⁺;Cosmc^f/+), and WT control (Vil-Cre⁺;Cosmc^{+/y OR +/+}) mice. (B) Sialyl-Tn expression was analyzed by monoclonal antibody on FFPE, swiss-rolled CR, and SI from KO, mosaic, and WT mice (distal segment in center of swiss-roll). (Scale bars: Left and Center, 200 μM; Right, 500 μM.) PAS/AB staining was performed on Carnoy’s fixed distal (magnification: 40×) and proximal (magnification: 10×) colon from WT, mosaic, and KO mice (C), and the inner mucus layer thickness was quantified in the distal colorectum (5 measurements per mouse per replicate, n = 5 mice per group) (D). n = 3–5 mice per group, age 3 mo (B and C). ****P ≤ 0.0001 from one-way ANOVA with Tukey’s post hoc test for multiple comparisons; mean ± SD.