PMC:2586094 / 7031-7572 JSONTXT

2.5 Immunoprecipitations and CK2 activity assays Whole cell extracts (150–300 µg) were prepared using buffers containing phosphatase and protease inhibitors and subjected to immunoprecipitation and in vitro kinase assays using the β-casein substrate as previously described [10]. For CK2 assays with Sp1, 0.5 µg of recombinant protein was used as a substrate instead of β-casein. For co-immunoprecipitation assays, the immunoprecipitated proteins were eluted using 0.1 M glycine (pH 2.5) and subjected to SDS-PAGE and western blot analysis.