Required for asymmetric spindle positioning; asymmetric oocyte division and polar body extrusion during female germ cell meiosis (By similarity). Actin-binding protein that is involved in actin cytoskeleton assembly and reorganization. Acts as an actin nucleation factor and promotes assembly of actin filaments together with SPIRE1 and SPIRE2. Involved in intracellular vesicle transport along actin fibers; providing a novel link between actin cytoskeleton dynamics and intracellular transport. Plays a role in responses to DNA damage; cellular stress and hypoxia by protecting CDKN1A against degradation; and thereby plays a role in stress- induced cell cycle arrest. Protects cells against apoptosis by protecting CDKN1A against degradation. {ECO:0000250; ECO:0000269|PubMed:22330775; ECO:0000269|PubMed:23375502}.