Figure 4

Dynamics of HP1 varies during cell cycle. Distribution of t1/2 values deduced from FRAP experiments for GFP-HP1β (upper panels), GFP-HP1γ (middle panels), and GFP-HP1α (lower panels) after serum starvation (A) or nocodazole treatment (B). The bars indicate the number of cells presenting a given t1/2 value. The effect of the treatments on cell synchronization is measured by FACS analysis (a-f). Nuclear localization of GFP-tagged HP1 proteins (G) and heterochromatin foci revealed by Hoechst staining (H) are shown. (C) Detection of GFP-HP1 and endogenous HP1 isoforms by Western blotting using specific antibodies for each isoform (α-HP1β, α-HP1γ and α-HP1α) in absence of treatment (Control), in presence of Nocodazole (50 ng/ml) 24 hours or after 72 hours serum starvation.