Heterogeneity in the trajectory of heterochromatin protein 1β (HP1β), B lymphoma Mo-MLV insertion region 1 (BMI1), and telomeric-repeat binding factor 1 (TRF1) foci at the nuclear periphery. Real-time monitoring of the foci trajectories is shown for HP1β (a), BMI1 (b), and TRF1 (c) foci. Trajectories were mapped for foci that occupy the nuclear periphery. Heterogeneity in movement of all foci (blue tracks) within an individual cell nucleus (grey) and events is shown. HP1β, BMI1, and TRF1 kinetics was studied in control cells, after TSA, actinomycin D, and vorinostat treatment. Observation was performed over 20 min, scanning was performed every 2 s. Each trajectory (blue curves) is bound by an ellipse enclosing the area of movement; the red star is the centre of the ellipse and the red circle is the start point of movement.