Bcr plays a pivotal role in cellular signaling pathways by functioning as a GTPase-activating protein (GAP) for Rac1 p21, thereby regulating cytoskeletal dynamics, cell migration, and proliferation. Structurally, Bcr contains multiple domains that facilitate interactions with key proteins such as c-Abl, forming the Bcr/Abl fusion protein in the Philadelphia chromosome translocation found in approximately 90-95% of chronic myelogenous leukemia (CML) cases. Additionally, Bcr interacts with adaptor proteins like Crk, which are essential for downstream signaling events that influence cell adhesion and movement. These interactions are crucial for maintaining normal cellular functions and preventing uncontrolled cell growth. The Bcr gene is located on chromosome 22 and its fusion with c-Abl on chromosome 9 leads to the constitutive tyrosine kinase activity of the Bcr/Abl fusion protein, driving the proliferation of leukemic cells.