FIGURE 5:

(A) Reduced oxygen increases the temporal tolerance for prometaphase prolonged up to 6 h. Asynchronous populations were treated with nocodazole for 6 h in medium equilibrated with 3% oxygen. After nocodazole removal, the daughter cells were followed at ambient oxygen levels. Significantly more daughters born of mothers spending >1.5 h in prometaphase proliferated relative to the basic experiment (Figure 2A): p = 1.5 × 10^–14. For the daughters born of mothers spending <1.5 h in prometaphase, there was no significant decrease in the proportion of cells that proliferated (p = 1.0). (B) In contrast, partial inhibition of MCL1 activity at reduced oxygen level diminishes the temporal tolerance for prolonged prometaphase. Cells were treated with MIM1 plus nocodazole at ∼3% oxygen for 6 h, and after washout of both drugs, daughter cells were continuously followed at ambient oxygen levels.