[5][6][7] The protein was identified in the laboratory of Xiaodong Wang as an activator of caspase-3 in the presence of cytochromeC and dATP.

[8] This gene encodes a cytoplasmic protein that forms one of the central hubs in the apoptosis regulatory network.

The apoptosome binds and cleaves Procaspase-9 protein, releasing its mature, activated form.

The precise mechanism for this reaction is still debated though work published by Guy Salvesen suggests that the apoptosome may induce caspase-9 dimerization and subsequent autocatalysis.

[citation needed] Alternative splicing results in several transcript variants encoding different isoforms.