Dab2 (DAB adaptor protein 2) also known as DOC2 is a mitogen-responsive phosphoprotein that binds the SH3 domain of GRB2, and it is thought to be a negative regulator of growth. Dab2 plays a crucial role in cellular signaling and growth regulation. Dab2 is primarily located in the cytoplasm, where Dab2 acts as a negative regulator of growth by binding to the SH3 domain of GRB2, an adaptor protein that couples tyrosine kinase receptors to SOS (a guanine nucleotide exchange factor for Ras), via its C-terminal proline-rich sequences, and may thus modulate growth factor/Ras pathways by competing with SOS for binding to GRB2.  Dab2 is expressed in normal ovarian epithelial cells, but is down-regulated or absent from ovarian carcinoma cell lines, suggesting its role as a tumor suppressor.