Fig. 7. A model for the activities of PTEN after recruitment to the PAR/aPKC complex. Recruitment of PTEN by Baz probably leads to local reduction of PtdIns(3,4,5)P₃ and a local increase of PtdIns(4,5)P₂ in the plasma membrane at the site where recruitment occurs. This should result in downregulation of the activities of aPKC and Cdc42, because PDK1, the kinase that activates aPKC, and guanine nucleotide exchange factors (GEFs) that activate Cdc42 are recruited to the plasma membrane via their PH domains by PtdIns(3,4,5)P₃. How exactly recruitment of PTEN to the PAR/aPKC complex would affect actin organization is difficult to predict, as both PtdIns(4,5)P₂ and PtdIns(3,4,5)P₃ are important effectors of actin dynamics. Proteins that bind to phosphoinositide lipids via PH domains are highlighted in red. Direct protein-protein interactions within the PAR/aPKC complex are indicated by double bars. ERM, ezrin, radixin, moesin; WASP, Wiskott-Aldrich syndrome protein; Arp2/3, actin related protein 2/3 (for reviews, see Pollard et al., 2000; Millard et al., 2004).