AXL and colitis: To compare the compositions of the gut microbiota between WT and Axl−/– mice after DSS administration, we sacrificed WT (WT-D8) mice on day 8 and Axl−/– (Axl−/– D5) mice on day 5 because the clinical symptoms of DSS-induced colitis occurred within 5 days in Axl−/– mice compared with 8 days in WT mice.