Figure 5.

MCF10A emerge from prolonged S phase arrest. MCF10A were treated with aphidicolin (96 h) and cell number monitored for a further 6 days in fresh medium to assess their return to proliferation (a). During recovery from arrest, changes in the expression of p21, cyclin D1 and pRb were monitored (b) and the return to proliferation confirmed by flow cytometry (compare profiles in c and d) and the declining expression of SA-β-galactosidase (e). Primary hMECs were treated for 4 d with or without aphidicolin and their cell cycle profiles analysed by flow cytometry (f). After removing aphidicolin, primary hMECs were grown for 4 d in fresh media and cell cycle profiles analysed (f, compare untreated (i) with aphidicolin treated and recovered (ii)). Cells treated with aphidicolin showed limited recovery from arrest (f), with accumulation of apoptotic cells relative to untreated controls (g). Scale bar 50 μm