D.Phil., Physiology, Oxford University
M.Sc., Biomedical Sciences, Bradford University
B.Sc., Biology, American University of Beirut


Dr Haj's laboratory studies the role of tyrosine phosphorylation and dephosphorylation in cell signaling and disease.   Research focuses on the function of protein-tyrosine phosphatases (PTPs) in regulating insulin signaling and how deregulation of these pathways leads to diseases such as obesity and type 2 diabetes.  This is achieved through the combined use of biochemical, cellular and knockout mouse studies.  Collectively, these approaches will enable the dissection of metabolic regulation at the cellular and organism levels.

Andrew Stoker, Bernhard Gehrig, Fawaz Haj and Boon-Huat Bay (1995).  Axonal localization of the CAM-like tyrosine phosphatase CRYPa: a signaling molecule of embryonic growth cones.  Development.  Jun, 121 (6): 1833-44.

Fawaz Haj, Iain Mckinnell and Andrew Stoker (1999).  Retinotectal ligands for the receptor tyrosine phosphatase CRYPa.  Molecular and Cellular Neuroscience.  Sep, 14 (3): 225-40.

Matthias Ledig, Fawaz Haj, John Bixby, Andrew Stoker and Bernhard Mueller (1999).  The receptor protein tyrosine phosphatase CRYPa promotes intraretinal axon growth.  Journal of Cell Biology.  Oct, 147 (2): 375-88.

Fawaz Haj, Peter Verveer, Anthony Squire, Benjamin Neel and Philippe Bastiaens (2002).  Imaging sites of receptor dephosphorylation by PTP1B on the surface of the endoplasmic reticulum.  Science.  Mar, 295 (5560): 1708-11.

Janice Zabolotny, Kendra Bence, Alain Stricker-Krongrad, Fawaz Haj, Young-Ping Wang, Yasuhiko Minokoshi, Young-Bum Kim, Joel Elmquist, Luois Tartaglia, Barbara Kahn, Benjamin Neel (2002).  PTP1B regulates leptin signal transduction in vivo.  Developmental Cell.  Apr, 2 (4): 489-95.

Fawaz Haj, Boyka Markova, Lori Klaman, Frank Bohmer and Benjamin Neel (2003).  Regulation of receptor tyrosine kinase signaling by protein tyrosine phosphatase-1B.  Journal of Biological Chemistry.  Jan 10, 278 (2): 739-44.

Gustavo Sajnani-Perez, John Chilton, Radu Aricescu, Fawaz Haj, Andrew Stoker (2003).  Isoform-specific binding of the tyrosine phosphatase PTPs to a ligand in developing muscle.  Molecular and Cellular Neuroscience.  Jan, 22 (1): 37-48.

Jake Kushner, Fawaz Haj, Lori Klaman, Mathew Dow, Barbara Kahn, Benjamin Neel and Morris White (2004).  Islet-sparing effects of protein tyrosine phosphatase-1b deficiency delays onset of diabetes in IRS2 knockout mice.  Diabetes.  Jan, 53 (1): 61-66.

Camilla Persson, Catrine Svenhed, Annie Bourdeau, Michel Tremblay, Boyka Markova, Frank Bhmer, Fawaz Haj, Benjamin Neel, Carl-Henrik Heldin, Lars Rnnstrand, Arne stman and Carina Hellberg (2004).  Site-selective regulation of platelet growth factor b receptor tyrosine phosphorylation by T-cell protein tyrosine phosphatase.  Molecular and Cellular Biology.  Mar 1, 24 (5): 2190-2201.

Janice Zabolotny, Fawaz Haj, Jason Kim, Young-Bum Kim, Gerald Shulman, Barbara Kahn and Benjamin Neel (2004).  Transgenic overexpression of protein-tyrosine phosphatase 1B in muscle causes insulin resistance, but overexpression with leukocyte antigen-related phosphatase does not additively impair insulin action.  Journal of Biological Chemistry.  Jun 4, 279 (23): 24844-51.

Sandra Galic, Christine Hauser, Barbara Kahn, Fawaz Haj, Benjamin Neel, Nicholas Tonks, and Tony Tiganis (2005).  Coordinated regulation of insulin signaling by the protein tyrosine phosphatases PTP1B and TCPTP.  Molecular and Cellular Biology.  Jan, 25 (2): 819-29.

Fawaz Haj, Janice Zabolotny, Young-Bum Kim, Barbara Kahn and Benjamin Neel (2005).  Liver-specific re-expression of protein-tyrosine phosphatase 1B reverses insulin sensitivity in PTP1B knockout mice.  Journal of Biological Chemistry.  Apr 15, 280 (15): 15038-46.

Elena Arias-Salgado, Fawaz Haj, Christophe Dubois, Barry Moran, Ana Kasirer-Friede, Barbara Furie, Bruce Furie, Benjamin Neel and Sanford Shattil (2005).  PTP-1B is an essential positive regulator of platelet integrin signaling.  Journal of Cell Biology.  Aug 29,170 (5): 837-45.

Shrikrishna Dadke, Sophie Cotteret, Shu-Chin Yip, Zahara Jaffer, Fawaz Haj, Alexey Ivanov, Frank Rauscher III, Ke Shuai, Tony Ng, Benjamin Neel, and Jonathan Chernoff (2007).  Regulation of protein-tyrosine phosphatase 1B through sumoylation.  Nature Cell Biology.  Jan, 9(1): 80-85.