SFLDLoader provides an interface to the [Structure-Function Linkage Database](http://sfld.rbvi.ucsf.edu) which is a highly curated database of mechanistically diverse superfamilies of enzymes. The SFLDLoader allows Cytoscape users to browse the available superfamilies, subgroups, and families and view the SFLD summary information for each. Users may select a superfamily or one or more subgroups or families to download the corresponding protein similarity networks into Cytoscape. A BLAST E-Value cutoff may be set to only load the most significant edges.