Depletion of MarvelD3 and tight junction assembly. (A) Control and siRNA-transfected Caco-2 cells were plated on filters one day after transfection. The cells were lysed three days later and expression of MarvelD3 and α-tubulin was determined by immunoblotting. (B) Cells treated as those in panel A were fixed and processed for immunofluorescence at the end of the incubation period. Shown are epifluorescence images of samples labelled for the tight junction markers occludin and ZO-1. Bar, 10 μm. Note, depletion of MarvelD3 did not affect monolayer integrity and appearance.