The effect of CD317 knockdown in polarized Caco-2 cells. (A) Left panels are maximum intensity projection XY images showing Alexa Fluor 594–phalloidin decoration of F-actin in polarized control and CD317 knockdown Caco-2 cells. Middle panels show XZ sections taken along the lines in left panels. Right panels show corresponding SEM images of the surface of control and CD317 knockdown cells. Arrows indicate the positions of the top (A) and bottom (B) of the cell monolayer. (B) ZO-1 labeling of tight junctions in polarized CD317 knockdown and control Caco-2 cells and biotin labeling of proteins in the apical membrane of polarized CD317 knockdown Caco-2 cells as indicated. Left panels are maximum intensity projection XY images, and right panels are XZ sections taken along the lines in the left panels. Arrows indicate the positions of the top (A) and bottom (B) of the cell monolayer. (C) Detection of β-catenin in the lateral membranes and sucrase-isomaltase in the apical membrane of polarized CD317 knockdown Caco-2 cells. XZ sections derived from maximum intensity projection XY images are presented. The right panel is a merge of the left and middle images. Bars, 10 µm.