Fig. 4

Nucleolar stress induces nuclear ErbB3 accumulation and affects cell viability. Nuclear extracts obtained from HeLa and U-87MG cells treated with 0,04 μg/ml of actinomycin D were analysed by western blot for the expression of ErbB3 and the nucleolar marker C23 (A). Densitometric quantification of the ErbB3 and C23 signals was performed with the Image J software (B-E). ErbB3 re-localizes to the nucleoplasm upon low Actinomycin treatment in U-87MG cell (F). Scalebar represent 50 μm. U-87MG cell survival, measured by trypan blue, was strongly affected after actinomycin D treatment (G). Remarkable changes are evident, after 72 h exposure to actinomycin D and overall cell shape and density (H). Scalebar represent 100 μm. Data are the average of three independent experiments and significant results are highlighted with asterisks (* p < 0.05, *** p < 0.001)