Essential hematopoietic-specific regulator of the actin cytoskeleton. Controls lymphocyte development, activation, proliferation and homeostasis, erythrocyte membrane stability, as well as phagocytosis and migration by neutrophils and macrophages (PubMed:19015308, PubMed:23424621). Component of the WAVE2 complex which signals downstream of RAC to stimulate F-actin polymerization (PubMed:23424621). Required for stabilization and/or translation of the WAVE2 complex proteins in hematopoietic cells (PubMed:19015308). Within the WAVE2 complex, enables the cortical actin network to restrain excessive degranulation and granule release by T-cells. Required for efficient T-lymphocyte and neutrophil migration (By similarity). Exhibits complex cycles of activation and inhibition to generate waves of propagating the assembly with actin. Also involved in mechanisms WAVE independent to regulate myosin and actin polymerization during neutrophil chemotaxis (By similarity). In T-cells, required for proper mechanistic target of rapamycin complex 2 (mTORC2)-dependent AKT phosphorylation, cell proliferation and cytokine secretion, including that of IL2 and TNF (By similarity). In hematopoietic cells, component of the WAVE2 complex composed of ABI1, CYFIP1/SRA1, NCKAP1L/HEM1 and WASF2/WAVE2. Interacts with ARHGAP4, PIK3C3/VPS34 and PPP1R12A/MYPT1. Interacts with mammalian target of rapamycin complex 2 (mTORC2) components, including MTOR and RICTOR. Localizes to the leading edge of polarized neutrophils. Predominantly expressed in developing and mature hematopoietic cells. Also detected in urogenital tissues, including testis. Mutants exhibit lymphopenia, neutrophilia and anemia. T cell development is disrupted at the CD4(-)CD8(-) to CD4(+)CD8(+) cell stages and T cell activation and adhesion are impaired. Neutrophils fail to migrate in response to chemotactic agents and are deficient in their ability to phagocytose bacteria. They show enhanced Th17 cells production (PubMed:19015308). The anemia is microcytic, hypochromic and characterized by abnormally shaped erythrocytes with aberrant F-actin foci and decreased lifespan (PubMed:23424621).