Weissman and his lab are investigating protein folding and probe the mysteries behind the organizational principles of biological systems through a variety of molecular and technological methods. While technologies like RNA-seq have made it much easier to monitor which genes are being expressed in a cell at any given time, these approaches use messenger RNA as a proxy for proteins. But generally it is proteins, and not RNAs, that mediate a gene’s cellular functions. That means RNA sequencing is an imperfect indicator for what is actually going on in a cell. To address this issue, Weissman developed a method called ribosome profiling, which measures the ribosomes active in a cell -- and the mRNA, soon to become proteins, inside them.