Plays an important role in the organization of the cytoskeleton. Binds to and sequesters actin monomers (G actin) and therefore inhibits actin polymerization (By similarity). Seraspenide inhibits the entry of hematopoietic pluripotent stem cells into the S-phase. Interacts with SERPINB1. Identified in a complex composed of ACTA1, COBL, GSN AND TMSB4X (By similarity). Originally found in thymus but it is widely distributed in many tissues. By NGF and fibroblast growth factors. Belongs to the thymosin beta family.