Figure 2. Ssu72 is essential for cell proliferation and viability in DT40 cells.

(A, B) Growth curve of DT40 wild-type (WT) and conditional mutant [P1 (−/−)] DT40 cells. WT (A) or P1 (−/−) (B) cells were seeded in triplicate in 12-well plates (5×10³ cells/well) in media with or without doxycycline (Dox), and split every 2 days. Concentrations of live cells were determined by Giemsa staining and counted at the indicated time points. Cell density is shown on a logarithmic scale. (C) WT cells (left) or P1 (−/−) cells (right) treated with Dox for 6 days (lower) or untreated (upper) were subjected to FACS analysis after staining with propidium iodide. Gates M1, M2, M3, and M4, delimited by the vertical bars above the FACS traces, indicate the cell-cycle distributions of the sub-G1, G0/G1, S and G2 populations, respectively.