Table 1. Pairs of candidate interacting proteins were evaluated using the split YFP system for their ability to generate specific fluorescence upon induction of apoptosis in MCF7 cells.

Protein pairs		YFP fluorescence
C-YFP	N-YFP	Baseline	Apoptosis
WD(APAF-1)–C-YFP	Cyt c–N-YFP	Low background	No change
XIAP–C-YFP	Smac–N-YFP	Low background	No change
C-YFP–Bax	MitoPLD–N-YFP	Low background	No change
C-YFP–Bax	Cyt c–N-YFP	Low background	High increase in mitochondria
C-YFP–Bax	Smac–N-YFP	Low background	High increase in mitochondria
C-YFP–Bax	N-YFP–Bax	Low background	High increase in mitochondria
Bid–C-YFP	N-YFP–Bax	High background in cytosol	Translocation to mitochondria

Apoptosis was induced by TNFα or etoposide. Fluorescence was followed by live-cell imaging using a DeltaVision system.