Comparison of caspase-3 activation by DCC-IC versus cytochrome
c. A dose-dependence analysis of DCC-induced caspase-3
activation was performed. In a similar in vitro assay as
in Fig. 4, different quantities of DCC-IC or cytochrome
c in the presence or not of 1 mM dATP were added. In the
case of DCC-IC, the concentration was estimated based on comparison
with purified protein (L.G. and P.M., unpublished data). Purified
cytochrome c was used as attempts to activate caspase-3
in vitro with in vitro-translated
cytochrome c were unsuccessful, probably as a result of
the absence of the cytochrome c-associated heme (C.F.
and P.M., unpublished results). The p20 cleavage fragment of caspase-3
was then detected by immunoblot and quantified by densitometry. A graph
of the level of caspase-3 activation is presented.