Cdc42 knockout cells form multiple brush borders and have dispersed recycling endosome localization. (A) Maximum intensity projections of polarized W4:NEC cells expressing dsRed-Rab11 and Lifeact-GFP. Bars, 5 µm. (B) Quantification of cells with multiple brush borders in polarized W4 cells or W4:NEC cells expressing YFP or YFP-Cdc42. Numbers in parentheses indicate total number of cells with multiple apical membranes in three independent experiments. Error bars are SEM from three experiments. *, P < 0.003. E.V., empty vector. (C) Quantification of brush border formation in W4:NEC cells. Error bars are SEM from three experiments. n.s., P > 0.05. (D) Western blot of W4 cell or W4:NEC cell lysates probed for Cdc42 and α-tubulin.