The Mendoza group’s research focuses on understanding basic principles of protein function relevant to human health and disease. Protein families of interest include the interferon (IFN) superfamily of cytokines which are an essential part of the innate immune system, providing protection against the spread of viral infections and cancerous growths. There are three families of IFNs, type I-III, each with distinct ligand-receptor systems. By applying a protein engineering approach, we are able to rapidly evolve IFNs and visualize the three-dimensional shapes of interferon cytokines bound to their cellular receptors. When the sequence and structural information of the newly evolved interferon cytokines is combined with comprehensive biophysical and functional studies, we provide new insights into cytokine signaling and create new opportunities for developing promising molecules for basic research and clinical use. Further work in the lab focuses on developing computational tools to accelerate protein engineering efforts and extend our understanding of the protein sequence-structure-function paradigm to other protein superfamilies.