1. What is the major issue addressed by this paper?
The radiation-induced bystander effect (RIBE) is a conserved phenomenon
RIBE is an important factor for radiosafety, radiation protection and radiotherapy
RIBE can inhibit programmed cell death and promote cell proliferation
What is RIBE factor?
Worm p53 homologue is critical for RIBE

2. Cathepsin B was identified as a RIBE factor
through genetic screens
through educational guess
through partial biochemical purification followed by mass spectrometry analysis and RNAi verification
through RNAi screen
Biochemical purification

3. Cathepsin B exerts RIBE on unexposed cells through
the ced-3 cell death protease
insulin-like receptor DAF-2
known DAF-2 signaling pathway
the p53 homologue CEP-1
All of the above

4. The RIBE induced by cathepsin B is
CEP-1-dependent
Cathepsin B protease activity-dependent
daf-2-dependent
dependent on the secreted form of cathepsin B
All of the above

5. Cathepsin B can be secreted to the extracellular space
is a cysteine protease
can mediate long-range signaling
can promote cell proliferation
All of the above

6. What are the most important questions that have not been addressed by this paper?
Substrates of cathepsin B
The downstream signaling pathway of cathepsin B
How cathepsin B inhibits cell death
How cathepsin B promotes cell proliferation
How cathepsin B causes stress response