Nutlin-3a suppresses senescence caused by low concentrations of IPTG.

HT1080-p21-9 cells were plated in 60 mm dishes at 5000 per dish with 2 ug/ml IPTG with or without 10 uM nutlin-3a as indicated. After 1 day, dishes on the right were treated with 200 nM nocodazole. After 3 days, cells were washed and incubated in drug-free medium for 4 days in control (to avoid overgrowth) and for 7 days for all other conditions. Then colonies were stained with crystal violet.