Like a building supported by a steel frame, a cell contains its own sturdy internal scaffolding made up of proteins, including microtubules. Researchers studying snapshots of microtubules have proposed a model for how these structural elements shorten and lengthen, allowing a cell to move, divide, or change shape. This picture shows an intermediate step in their model: Smaller building blocks called tubulins peel back from the microtubule in thin strips. Knowing the operations of the internal scaffolding will enhance our basic understanding of cellular processes. Courtesy of Eva Nogales, a structural biologist at the University of California, Berkeley.