They were resuspended in buffer1 (0.32 M sucrose, 10 mM Tris, pH8.0, 3 mM CaCl2, 2 mM Mg-acetate, 0.1 mM EDTA, 0.5% NP40, 1 mM DTT, 0.5 mM PMSF; 1 × 107cells/400μl buffer) and sonified on ice (sonifier UP200S, dr.hielscher, 40 s, amplitude 50%, cycle 0.5).