Abbreviations used in this paper: AJ, adherens junction; APF, after puparium formation; aPKC, atypical PKC; Baz, Bazooka; CAT, catalytic domain; Crbs, Crumbs; DE-cadherin, Drosophila epithelial cadherin; Dia, Diaphanous; Dlg, Discs large; DN, dominant negative; Flp, flippase; GAP, GTPase-activating protein; GEF, guanine nucleotide exchange factor; GMR, glass multimer reporter; hsFLP, heat shock Flp; LOF, loss-of-function; MARCM, mosaic analysis with a repressible cell marker; MLC, myosin light chain; MRCK, myotonic dystrophy kinase-related Cdc42-binding kinase; Mtl, Mig-2 like; Pak, p21-activated kinase; PEC, pigment epithelial cell; Rok, Rho-associated kinase; Scrib, Scribble; SJ, septate junction; Ssh, slingshot; Tsr, twinstar; UAS, upstream activating sequence; Wsp, Wiskott-Aldrich syndrome protein; WT, wild type.