Joan Steitz is interested in noncoding RNA-protein complexes, which are ubiquitous in eukaryotic cells and inhabit specific cellular compartments. Steitz and her team are particularly interested in small nuclear ribonucleoproteins, or snRNPs. These tightly bound complexes participate in pre-RNA splicing, an early step in gene expression. The team seeks to understand the biogenesis, mechanisms, and function of these and other nuclear RNA machines, including those where the RNA is made by an infecting virus. The work has relevance for understanding cancer-causing viruses such as the Epstein-Barr virus and Kaposi’s sarcoma-associated herpesvirus.