mDia1 (also known as Dia1, Drf1 for Diaphanous-related formin-1, Diaph1, KIAA4062, p140mDia, mKIAA4062, or D18Wsu154e) is a member of the protein family called the formins and is a Rho effector. It is the mouse version of the diaphanous homolog 1 of Drosophila. mDia1 localizes to cells' mitotic spindle and midbody, plays a role in stress fiber and filopodia formation, phagocytosis, activation of serum response factor, formation of adherens junctions, and it can act as a transcription factor. mDia1 accelerates actin nucleation and elongation by interacting with barbed ends (fast-growing ends) of actin filaments. The gene encoding mDia1 is located on Chromosome 18 of Mus musculus and named Diap1. mDia1 (also known as Dia1, Drf1 for Diaphanous-related formin-1, Diaph1, KIAA4062, p140mDia, mKIAA4062, or D18Wsu154e) is a member of the protein family called the formins and is a Rho effector. It is the mouse version of the diaphanous homolog 1 of Drosophila. mDia1 localizes to cells' mitotic spindle and midbody, plays a role in stress fiber and filopodia formation, phagocytosis, activation of serum response factor, formation of adherens junctions, and it can act as a transcription factor. mDia1 accelerates actin nucleation and elongation by interacting with barbed ends (fast-growing ends) of actin filaments. The gene encoding mDia1 is located on Chromosome 18 of Mus musculus and named Diap1. mDia1 is highly homologous to Drosophila diaphanous, regulating the cytokinetic ring during cytokinesis. Homologues in other species are known as well, like the human DIAP1, budding yeast Bni1 or fission yeast Cdc12p. The gene has been knocked-out in mice. The product of the Diap1 (Diaph1) gene consists of 1255 amino acids resulting in a molecular weight of 139,343 daltons. The mDia1 polypeptide chain can be divided into four protein domains: