23) Why is thymosin needed in a cell? A) Thymosin modulates high cellular concentration of G- actin. B) Thymosin recharges actin from the ADP to ATP form. C) Thymosin balances high G-actin concentrations by promoting depolymerization. D) Thymosin caps F-actin and it does not allow polymerization even at high G-actin concentrations. 24) How many of these are function of the ECM? anchoring cells; controlling cell polarity; facilitating cell migration; binding growth factors A) 1 B) 2 C) 3 D) 4.