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. 2003 Jan;23(1):389–401. doi: 10.1128/MCB.23.1.389-401.2003

FIG. 7.

FIG. 7.

Bmi-1 overexpression extends replicative life span in low O2 concentrations. (A) Presenescent WI-38 cells (PD 24) were cultured for 2 weeks in 3% O2, infected with control (B0) or Bmi-1 (B-Bmi1)-expressing retrovirus, and selected in 3% O2. Half the control culture (B0) was moved to 20% O2 on the day indicated by the dashed arrow. All cells were passaged until senescence. The solid arrow indicates the day of superinfection (B). (B) A control culture (B0) was superinfected with murine stem cell retroviruses carrying no insert (M0) or Bmi-1 (M-Bmi-1) in either in 3 or 20% O2. Cells were selected in hygromycin and passaged until senescence. (C) Presenescent cells (PD 24) were cultured in 3 or 20% O2 for 2 weeks and infected with retroviruses carrying no insert (B0) or Bmi-1 (B-Bmi-1) in either 3 or 20% O2. Cells were selected and passaged for 1 week. p16, p21, and α-tubulin (control) expression was determined by Western analysis. Three independent experiments showed similar results.