TRAF6 deficiency abolishes the expression of FAE-associated genes. (A) The expression of FAE-associated genes (Ccl20, Cxcl16, Psg18, and Ubd) in Traf6^f/f and Traf6^IEC-KO mice was analyzed (normalized with Gapdh, mean ± SD; n = 5). Solid symbols indicate the data of Traf6^f/f mice, whereas open ones indicate those of Traf6^IEC-KO mice. (B) In the same sample sets as A, the expression of mucus-associated genes was examined by quantitative PCR. (C) PPs of Traf6^f/f and Traf6^IEC-KO mice were immunostained with anti–CCL20 antibody (green). Nuclei were counterstained with DAPI (blue). Dotted lines indicate the FAE. Bars, 20 µm. (D) Sections of the small intestine from Traf6^f/f and Traf6^IEC-KO mice were stained with alcian blue to visualize mucus-secreting cells. Bars, 50 µm. Data are representative of two independent experiments.