Fig. 6. Distribution and dynamics of HP1 proteins in wild-type and mutant MEFs. (A) Localization of endogenous HP1, HP1, HP1 and me₃K9-histone H3 in wild-type MEFs (WT) and HP1-HP1 double null mutants (^–/^–). Propidium iodide (PI) and antibody staining (Ab) are shown. (B) Western blot on WT and ^–/^– cells with the three anti-HP1 antibodies. (C) Distribution of HP1-GFP protein variants in the two cell types used above. Propidium iodide (PI) and GFP fluorescence are shown. Notice the different distribution of HP1-GFP in WT and ^–/^– cells. (D) The average number of HP1 foci (2 µm or greater in diameter) in transfected cells. (E) FRAP data from transfected WT and ^–/^– cells. rt_1/2 is the ratio of the half-times in the two cell types; im. fr. is the immobile fraction. Bar, 5 µm.