Protein-based drugs must be transported into cells in a way that prevents their immediate degradation. A new approach is intended to ensure that they remain intact only in certain cells, such as cancer cells. In a study published in the journal Angewandte Chemie International Edition, a Japanese research team has introduced a nanocarrier that can "escape" from endosomes before its cargo is destroyed there. This ability to escape is only triggered within the endosomes of certain tumor cells.