Figure 6. Expression of adenovirus E4orf4 protein strongly delays p107 dephosphorylation induced by FGF.

FLAG-tag E4orf4 was stably introduced into RCS cells. Growing cultures were treated with FGF1 for indicated periods of time. (A) E4orf4 forms a stable complex with PP2A when overexpressed in RCS cells. RCS cells overexpressing FLAG-tag E4orf4 and the parental cell line were treated with FGF. E4orf4 was immunoprecipitated with ANTI-FLAG® M2-Agarose and immunoprecipitated complexes were analyzed using PP2A-A, PP2A-C or FLAG antibodies as indicated. PP1 antibody was used as a negative control. As a reference 5% of the immunoprecipitated whole cell extract (“input”) was loaded. (B) 20 µg of total protein were subjected to immunodetection by p107 antibody.