FH proteins control rearrangements of the actin cytoskeleton, especially in the context of cytokinesis and cell polarisation. Members of this family have been found to interact with Rho-GTPases, profilin and other actin-assoziated proteins. These interactions are mediated by the proline-rich FH1 domain, usually located in front of FH2 (but not listed in SMART). Despite this cytosolic function, vertebrate formins have been assigned functions within the nucleus. A set of Formin-Binding Proteins (FBPs) has been shown to bind FH1 with their WW domain.