FIG. 6.

Expression of a dnHP1 reactivates silent GFP. (A) Map of dnHP1. Chromo, chromodomain. (B) A retroviral vector encoding a dnHP1 (60) was used to infect HeLa TI-C cells. Cells were placed under selection with puromycin and were monitored for reactivation of GFP expression by FACS. The FACS profile obtained at 5 days postinfection shows GFP expression in cells selected with the dnHP1 expression vector (no fill) versus the empty vector (filled). The expression of dnHP1 produced a population of GFP-positive cells (24%), some of which were very bright and appear off scale in the graph. A representative experiment is shown.