Plays an important role in the organization of the cytoskeleton (PubMed:1999398, PubMed:10848969). Binds to and sequesters actin monomers (G actin) and therefore inhibits actin polymerization (PubMed:1999398, PubMed:10848969). Potent inhibitor of bone marrow derived stem cell differentiation (PubMed:7694679). Acts by inhibits the entry of hematopoietic pluripotent stem cells into the S-phase (By similarity). Identified in a complex composed of ACTA1, COBL, GSN AND TMSB4X (PubMed:23009842). Interacts with SERPINB1 (By similarity). Expressed in several hemopoietic cell lines and lymphoid malignant cells. Decreased levels in myeloma cells. By alpha interferons. Decreased levels in THP-1 cells after treatment with recombinant interferon-lambda. AcSDKP is inactivated by ACE, which removes the dipeptide Lys-Pro from its C-terminus. Belongs to the thymosin beta family.