caspase-3 cleavage assay - how to test the clevage of a protein by caspase in vitro (Apr/14/2008 )

Hello everyone,
actuelly, i am trying to test a certain protein (normally cleaved by caspase-3).
I need to do the cleavage of this protein in vitro starting from a cellular extract in order to analyse its fragments by westen blot.
all the kits i found were for screening inhibitors' activity or caspase activity and they are not very compatible to cell extracts and western blots.
i really need a good protocol to to know what exactly to buy to do this test
has anyone already do a similar assay, can i use any caspase-3 enzyme product and incube it with the cell extract..
any idea about good product of it
sorry for annoying u with all these questions
any suggestion will be appreciated
wish u all a nice day

May be you can try some recombinant Caspase-3 protein?

Do you have any specific commercial products to recommend?
thanx
have a good day