Briefly, radiolabeled cell lysates (1 ϫ 10 5 cell equivalents) were diluted in 1 ml RIPA buffer (0.5% Triton X-100, 0.1% SDS, 300 mM NaCl, 4 mM EDTA, and 50 mM Tris-HCl, pH 7.4) and immunoprecipitated with 2 l of nsp-specific antibodies and protein A Sepharose beads (GE Healthcare).