Activation of Raf-1 is defective in annexin 6 overexpressing Chinese hamster ovary cells

Annexin 6 is a Ca2+-dependent phospholipid-binding protein involved in memb rane trafficking. In this study we demonstrate the association of Raf-1 wit h recombinant rat annexin 6, Raf-annexin 6 interaction was shown to be inde pendent of cell activation by epidermal growth factor (EGF) or phorbol este rs (12-O-tetradecanoyl-phorbol-13-acetate (TPA)), A stable Chinese hamster ovary (CHO)-anx6 cell line overexpressing annexin 6 was established to exam ine the function of annexin 6, In these cells, no increase of Ras-GTP level s, induced by EGF or TPA, was detected, In addition, the activity of Raf wa s completely inhibited, whereas the mitogen-activated protein kinase-P was unaffected. (C) 2001 Federation of European Biochemical Societies. Publishe d by Elsevier Science B.V. All rights reserved.