The directionality control in chemotaxis is the result of a reciprocal regulation of PI3-kinase and PTEN subcellular localization. MK2(-/-) neutrophils have a directionality loss in fMLP-induced chemotaxis. We found that in polarized WT neutrophils PTEN was localized in the uropod region. However, MK2(-/-) neutrophils or p38 MAPK inhibitor-SB203580-pretreated WT neutrophils showed a disrupted PTEN subcellular localization. Some PTEN was localized at the leading edge of the polarized neutrophils, which may lower the concentration of PI3-kinase lipid product PtdIns(3,4,5)P3 required for directionality sensing. FMLP-stimulated MK2(-/-) neutrophils or S13203580-pretreated WT neutrophils also had disrupted F-actin polarization. F-actin polymerization inhibitor lantrunculin-13 disrupted the polarization of PTEN, but not PtdIns(3,4,5)P3. The results suggest that PTEN uropod polarization is F-actin polymerization-dependent and may be through the effect of MK2 on F-actin polarization. (C) 2004 Elsevier Inc. All rights reserved.