Coimmunoprecipitations. 293T cells grown in 6 cm dishes were transfected with 1.5 μg of indicated expression vectors. Thirty six h later, cells were lysed at 4 °C in 650 μl of 50 mM Tris, pH 8, 150 mM NaCl, 50 mM NaF, 0.25 mM Na3VO4, 0.2 mM dithiothreitol, 0.5% Igepal CA-630, 10 μg/ml leupeptin,