TIAM1 is a human protein modulates the activity of Rho GTP-binding proteins and connects extracellular signals to cytoskeletal activities. Acts as a GDP-dissociation stimulator protein that stimulates the GDP-GTP exchange activity of Rho-like GTPases and activates them. Activates RAC1, CDC42, and to a lesser extent RHOA.

It is tightly associate with BAIAP2 as a subunit. It was found in virtually all analyzed tumor cell lines including B- and T-lymphomas, neuroblastomas, melanomas and carcinomas. It contains one DH (DBL-homology) domain, one PDZ domain, two PH domains and one Ras-binding RBD domain.Found in virtually all analyzed tumor cell lines including B- and T-lymphomas, neuroblastomas, melanomas and carcinomas.