Colon tissues were harvested and fixed in 10% formalin. Deparaffinized colon sections were then obtained and incubated with mouse anti-IRF4 Ab (Invitrogen) followed by Alexa546-conjugated anti-mouse IgG Ab (Invitrogen) by using Can Get Signal immunoreaction enhancer solution (Toyobo) as described previously 43 (link). For visualization of interaction between IRF4 and RICK, MyD88, TRAF6 in colon samples, a Duolink In Situ kit was used (Olink Bioscience). Goat anti-IRF4 Ab (Santa Cruz), rabbit anti-RICK Ab, rabbit anti-MyD88 Ab, and rabbit anti-TRAF6 Ab (Abcam) were used to visualize target protein interactions. For visualization of interaction between IRF4 and RICK, MyD88, TRAF6 in human DCs, cells were fixed in 4% paraformaldehyde and subjected to the protocols suggested by the Duolink In Situ kit.