A collaborative Bridge Project team, led by MIT biologist Amy Keating and Dana-Farber Cancer Institute physician-scientists Loren Walensky and Anthony Letai, describe a novel strategy for inhibiting Mcl-1, a protein that is often overexpressed in cancer and contributes to tumor cell survival and resistance to chemotherapy. The team modified small protein fragments, or peptides, using chemical approaches and sequence optimization techniques, to produce peptides that are stable and can enter cells. When administered to cancer cells that are dependent on Mcl-1 for survival, the peptides successfully induced cell death. This research, published in PNAS, could lead to the development of new drugs for many different cancer types, and thus holds significant promise for clinical translation.