Treatment of Myo5b KO intestinal explants with Dyngo resulted in an increase in inclusions contiguous with the apical membrane. (A) Two to four pieces of small-intestinal tissue (duodenum and jejunum) were mounted from each mouse into individual Üssing chambers to ensure tissue viability of explants. In small-intestinal explants from control mice, no inclusion formation was observed at the apical membrane after 4 h of incubation with Dyngo (n = 5 control mice). In Myo5b KO intestinal explants, administration of Dyngo resulted in numerous F-actin–rich (red) inclusions that failed to excise from the apical membrane (n = 4 Myo5b KO mice). Scale bars = 5 µm. (B) The percentage of inclusions attached to the apical membrane of enterocytes of Myo5b KO mice treated with DMSO (vehicle) and Dyngo was calculated by counting the number of inclusions contiguous with the apical membrane and the total number of inclusions in individual mice (n = 4 Dyngo-treated Myo5b KO mice and n = 5 DMSO-treated Myo5b KO mice). Treatment with Dyngo resulted in significantly more inclusions remaining at the apical membrane in Myo5b KO explants. (C) To confirm a decrease in internalization of inclusions in Myo5b KO mouse explants treated with Dyngo, 70-kD FITC-dextran was added to the apical media of each explant treated in the presence of Dyngo or DMSO. The percentage of inclusions containing FITC-dextran in each explant treated with DMSO or Dyngo was calculated by quantifying FITC-dextran–positive inclusions and total inclusions. Addition of FITC-dextran to the apical media of each explant resulted in fewer inclusions containing FITC-dextran in Myo5b KO explants treated with Dyngo. *, P < 0.05. One-sided Student’s t test was performed for B and C; error bars are SEM.