I am studying apoptosis whch is induced by drugs or serum starvation.
I found that PARP is cleaved by these apoptotic stimuli in breast cancer cells but this cleavage peaked at certain time point and the cleaved form decreases. Please see my western blot image.
I assumed that PARP cleavage would keep increasing during apoptosis process unless cells are completely dead and proteins start to be degraded. However, in my western blot, PARP cleavage peaked at 24hr starvation and went down at 72hr. When I harvested the cells at 72hr, cells did not look completely dead because they are all attached to the bottom and morphology was not changed. Also, equal loading indicates that there is no significant protein degradation is going on at 72hr starvation (or cleaved PARP is extremely labile??).
Could anyone explain why PARP cleavage decreases after peaked during apoptosis? Thanks!
Edited by cancerous, 07 March 2012 - 06:08 PM.