The Bcr gene was orginally identified by its presence in the chimeric Bcr-Abl oncogene (1). The N-terminal part of Bcr contains an oligomerization domain, a serine/threonine kinase domain and a region that binds SH2 domain. The middle of the protein has a PH domain and a region of sequence similarity to the guanine nucleotide exchange factors for the Rho family of GTP binding proteins. The C-terminal part may be involved in a GTPase-activating function for the small GTP-binding protein Rac (2,3). The function of Wildtype Bcr in cells remains unclear. PDGF receptor may use Bcr as a downstrean signal mediator (4). The Bcr-Abl fusion results in production of a constitutively active tyrosine kinase, which causes chronic myelogenous leukemia (CML) (5). Tyrosine 177 of Bcr is phosphorylated in Bcr-Abl fusion protein, which plays an important role in transforming the activity of Bcr-Abl (6). Phosphorylated tyrosine 177 of Bcr provides a docking site for Gab2 and GRB2 (7,8).