Nearly all the body’s cells contain identical DNA. So why does a neuron grow up so differently than a liver cell? Proteins are the key, says Akhilesh Pandey, a professor at the Johns Hopkins University. This week, two papers in Nature (one by Pandey’s team) catalog where in the body certain proteins are found. But what matters isn’t just where proteins show up—it’s how they twist and fold, says David Pincus, a fellow at MIT’s Whitehead Institute. Protein misfolding, for example, is a hallmark of neurodegenerative disease.