FNBP1 is a 617 amino acid protein that localizes to a variety of locations within the cell, including the cytoplasm, cytoskeleton, lysosome and the cell cortex, and contains one FCH domain, one REM repeat and one SH3 domain. Expressed at high levels in respiratory, reproductive and urinary systems, as well as in brown adipose tissue and epithelial cells of the gastrointestinal tract, FNBP1 interacts with Rho 7 and links the Actin cytoskeleton with Rho 7 signaling, playing a crucial role in membrane tubulation and cytoskeletal reorganization during endocytosis. Additionally, FNBP1, which exists as four alternatively spliced isoforms, enhances Actin polymerization and promotes membrane invagination and the formation of tubules. Chromosomal aberrations in the FNBP1 gene are associated with acute leukemias, suggesting a role for defective FNBP1 in carcinogenesis.