TIAM 1 ( T - cell lymphoma invasion and metastasis 1 )

Note Rho-like GTPases belong to the Ras superfamily and have crucial roles in many cellular processes, such as regulation of the actin cytoskeleton, cell migration, cell cycle progression, gene transcription and cell adhesion. Rho-like GTPases cycle between a GDP-bound inactive form and a GTP-bound active form and activation is catalysed by guanine nucleotide exchange factors (GNEFs) (Minard et al., 2004). The GNEF Tiam1 has been identified as an invasionand metastasis-inducing gene in a murine T-lymphoma cell line and specifically activates the Rho-like GTPase Rac. Tiam1/Rac signaling controls the establishment and maintenance of E-cadherin-based cell-cell adhesions and loss of Tiam1 leads to epithelialmesenchymal transition (EMT). Consequently, Tiam1/Rac signaling affects cell migration, invasion and tumor metastasis, but to some extent these effects seem to be cell typeand tumor type-dependent (Ellenbroek et al., 2007). Moreover, Tiam1 and Rac have been implicated in oncogenic transformation of cells.