Prolonged Tween-20 treatment leads to apoptosis.

<p>HeLa cells were incubated in serum-free DMEM (Untreated), serum-free DMEM containing 150 µM Tween-20, or serum-free DMEM containing 25 µM etoposide. The cells were harvested at the time points indicated, lysed and 40 µg of cell lysate was separated by electrophoresis on a 10% SDS-PAGE gel. Western blot analysis was performed to monitor PARP cleavage.