Timozin β4 je vseprisoten, 43-aminokislinski polipeptid z molekulsko maso 4.9 kDa. Je zelo ohranjen med vrstami, in se nahaja v vseh tkivih in vrstah celic razen v rdečih krvnih celicah. Timozin β4 je multifunkcionalni protein, ki pospešuje celično migracijo, pridobivanje in diferenciacija matičnih celic, proizvodnja proteaze, in izražanje različnih regulatornih genov, such as laminin-332, fibronectin, zyxin, VEGF, matrix metalloproteases, hepatocyte growth factor, and antioxidative enzymes (Table 1). It inhibits inflammation, microbial growth, scar formation (by reducing the level of myofibroblasts), and apoptosis, and protects cells from cytotoxic damage, including glutamate neuronal toxicity.Thymosin β4 binds to G-actin, blocks actin polymerization, and is coreleased with factor XIIIa by platelets, suggesting its importance in wound healing.