Figure 2.
STAT1β interacts with STAT1α to protect STAT1α from proteasome degradation. (a) STAT1α mRNA expression was detected by real-time PCR after transfection of empty vector or Flag-tagged STAT1β or STAT1βY701F plasmids. Values were normalized to GAPDH and calculated relative to empty vector-transfected cells. Mean values and standard errors (SE) from at least three independent experiments are shown. (b) Immunoprecipitation–immunoblotting analysis was performed for STAT1α and ubiquitination in EC1 cells transfected with empty vector or Flag-tagged STAT1β or STAT1βY701F plasmids. (c) The interaction of STAT1α and STAT1β was investigated by immunoprecipitation and western blot analysis in EC1 cells with or without IFN-γ stimulation. Co-immunoprecipitaion was carried out with control IgG and anti-Flag or anti-STAT1α antibodies as indicated. Immunoprecipitated proteins were analyzed by western blot with anti-STAT1α and anti-Flag, respectively. (d) Co-localization of STAT1α and STAT1β in vivo. EC1 and KYSE150 cells were placed on coverslips and stained with the indicated antibodies (scale bar 5 μm)