sentences:  The idea behind this is that, if survivin binds physically with the caspase it is incubated with, it will be co-precipitated along with the survivin while everything else in the lysate is washed away.The immunoprecipitates were then run on SDS-PAGE and then immunoblotted for detection of the desired caspase.If the caspase of interest was detected, it meant that it was bound to survivin in the immunoprecipitation step implicating that survivin and the particular caspase had bound beforehand.