2.3. Functional Enrichment Analysis with STRING and KEGG

These common, differentially expressed genes were then inputted into the STRING Protein Interactome (https://string-db.org/) to gain a stronger understanding of certain enriched functions that they belonged to. The STRING database compiles direct and indirect interactions among proteins from various sources and generates a diagram showing significant protein–protein interactions (PPIs) (Supplementary Figure S1). Gene ontology resources, such as GeneCards (https://www.genecards.org/) and the Human Protein Atlas (https://www.proteinatlas.org/), were used to find parallels between the functions of these genes and potential cellular pathways that are compromised in ALS and that are important in oculomotor neuron function. Once the collections of genes with apparent enriched PPIs were identified, their respective pathways were further analyzed using the Kyto Encyclopedia of Genes and Genomes (KEGG, https://www.genome.jp/kegg/) database, which helped to find parallels between enriched oculomotor and ALS pathways.