Therapeutic proteins for inducing apoptosis in cells and method for using such proteins are described. The protein, e.g., a chimeric protein, has a host peptide fused to a more stable BH3 domain peptide. The host peptide may be Calbindin D9k, a N-terminal or C-terminal half-domain of Calmodulin, Parvalbimin (“Pa”), an amino acid sequence variant thereof, or a modified variant thereof. The BH3 domain may be Bim, Bid, Bad, Bik, Bmf, Hrk, Puma, or Noxia. Moreover, various conjugates may be attached to the chimeric protein, including a folate and polyethylene glycol.
