Western blot analysis of co-immunoprecipitation experiments. Extracts were prepared from cells expressing various EGFP-p66 fusion proteins as described in the Methods section and immunoprecipitation carried out as described. Cells were transfected with constructs expressing EGFP or EGFP fusions as indicated. "control" indicates non-transfected cells. Panel A: immunoprecipitation was carried with a rabbit polyclonal anti-EGFP antibody (Ab290, Abcam). Bound proteins were separated by SDS-PAGE and Western blot analysis carried out with a mouse anti-PCNA antibody (PC10). Panel B: immunoprecipitation was carried out with a rat anti-p50 antibody and the blot probed with a mouse anti-GFP antibody (Roche). Panel C: immunoprecipitation was carried out with a rat anti-p50 antibody and the blot probed with a mouse anti-PCNA antibody (PC10).