Formins play an important role in the nucleation of actin and the formation of linear actin filaments. Interacts (via GBD/FH3 domain) with activated Rho-GTPases. Interacts with pfyA and pfyB. Expression decreases after the onset of development. 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). No visible phenotype. ForA and forB double null cells also show no phenotype. Belongs to the formin homology family. Diaphanous subfamily.