Background: Tec is a member of the Tec family of non-receptor protein-tyrosine kinase (PTK) which also includes Btk, emtk/itk/Tsk, Rlk/Txx and Bmx (1). Tec is composed of a pleckstrin domain (PH), an SH3 and SH2 domain, a catalytic kinase domain and a Tec homology domain (TH) (2). Tecs TH domain interacts with the SH3 domain of Grb2, Src family PTKs ( Fyn, Lyn, and Hck), Vav, and c-Kit. Tec is mostly expressed in hematopoietic cells. Tecs SH3 domain interacts with DC28 and has been shown to phosphorylate p62 dok, CD28 substrate (3). Tec can phosphorylate Jak kinase in hematopoietic cells (4) and can also be phosphorylated by Src member Lyn on multiple tyrosine residues (5).