The present invention provides novel peptides, nucleic acids, compounds, compositions and methods for regulating apoptosis, and screening methods for identifying same. Regulation of apoptosis is mediated via IAPi-derived proteins, peptide fragments thereof, and nucleic acids encoding same, stimulating/accelerating or downmodulating/suppressing apoptosis. For stimulation/acceleration of apoptosis, the IAPi-derived proteins or peptide fragments thereof comprise RHG and Trp-box amino acid consensus sequences. Stimulation/acceleration results in self-ubiquitination and auto-degradation of an IAP. For downmodulation/suppression of apoptosis, IAPi-derived proteins or peptide fragments thereof comprising either RHG or Trp-box amino acid consensus sequences, or both, failing to stimulate or suppressing self-ubiquitination and auto-degradation of an IAP, result in suppression of apoptosis.