SDS-PAGE (12.5% polyacrylamide gel) of rATB. Lanes: 1: molecular size markers; 2: E. coli BL21 (pET28arATB) prior to induction; 3: E. coli BL21 (pET28arATB) after induction; 4: 5 μ g denatured rATB in inclusion bodies; 5: 1 μ g refolded soluble rATB.