CSB428H1F Article #4: Martin-Belmonte et al. PTEN control PIP and Cdc42 Introduction PTEN localizes to apical PM to increase PI45P by decreasing levels of PI345P . Ectopic PI45P at 2 3 2 basolateral surface cause apical proteins to relocate to basolateral side. Annexin 2 (Anx2) binds PI45P and i2 recruited to apical surface to bind Cdc42, which recruits aPKC. Loss of PTEN, Anx2, Cdc42 or aPKC prevents apical surface and lumen formation. Madin-Darby-canine kidney (MDCK) cells embedded in gels for cysts with lumen. PI45P a2d PTEN localize to AP PM PH domain of PLC fused to GFP (PHD-GFP) detects PI45P . PHD-GFP localized mainly to AP PM 2 and little bit in BL PM, similar to that of actin. PH-Akt-GFP detects both PI34P and PI345P which are enriched at BL PM. 2 2 Before lumen formation, PI345P and3PI45P local2zed to cell-cell and cell-ECM contacts. During lumen formation, PI45P be2ame confined to AP PM, but PI345P became e3clusive to BL.