Plays a role in the regulation of cell morphology and cytoskeletal organization. Required in the cortical actin filament dynamics. The DAD domain regulates activation via by an autoinhibitory interaction with the GBD/FH3 domain. This autoinhibition is released upon competitive binding of an activated GTPase. The release of DAD allows the FH2 domain to then nucleate and elongate nonbranched actin filaments (By similarity). Belongs to the formin homology family. Aberrant splicing. Aberrant splicing.