Design and Evolution of a Miniature Bcl-2 Binding Protein We thank the HHMI Biopolymer/Keck Foundation Biotechnology Resource Laboratory (Yale University School of Medicine, New Haven, CT) for oligonucleotide and peptide synthesis and amino acid analysis and Professor Jennifer Doudna (Yale University) for use of a Perseptive Voyager-DE (MALDI-TOF) mass spectrometer. We are grateful also to Dr. Junying Yuan and Dr. Alexi Degterev (Harvard Medical School) for a generous gift of Bcl-X(L)-His(6) and Stacey E. Rutledge for helpful comments. This work was supported by the National Institutes of Health.