FIGURE 7. Id1 expression diminishes λ_R/E2A colocalizations in G1 phase.

A. Effect of Id1 expression on cell cycle-dependence of λ_R/E2A colocalizations. The Colocalizations in DT40 PolyLacO-λ_R RFP-LacI cells and a derivative stably expressing Id1 (Id1 − and +, respectively) in each stage of cell cycle are graphed, showing the percent of total cells in which colocalizations were evident. Note that Id1 expression diminished total colocalizations by about half.

B. Effect of Id1 expression on cell cycle-dependence of λ_R/P*-Pol II colocalizations. Details as in Figure 7A.

C. Fluorescence analysis of Id1-GFP levels in the course of cell cycle. DT40 cells were transiently transfected with Id1-GFP or its derivative carrying mutations in the D-box, which determines cell cycle-dependent instability; and GFP intensity and DNA content analyzed at 24 hr posttransfection. Fold increases of mean GFP fluorescence intensity in Id1^DBM-GFP relative to Id1-GFP is shown in the rightmost panel.