CDC42 and cyst: Cdc42 silencing caused dilated spherical lumina (Fig. S2 c); however, Rab35 knock-down yielded the most striking phenotype, causing the appearance of epithelial tubes (white arrowhead, Fig. 5 b) and large cyst-like structures (yellow arrowhead, Fig. 5 b) compared with control (Luciferase, siLuc; Fig. 5, a and b; and Fig. S2 d).