Activity values and structure files for 12 456 compounds tested with the p38 kinase was retrieved from PubChem. To limit the tested compounds to the strongest inhibitors, only those with an activity value (IC50, Kd, Ki) less than 100 nM were considered. These compounds were then analyzed with the MOE Since clustering is based on the molecule's 3D structure, the structure files inputted to the software had to include 3D coordinates. So, we converted SMILES, which are a structural representation consisting of one-dimensional ASCII strings, into a 3D Spatial Data File (SDF) format using the CACTUS Structure Files Generator. The SDF files were then imported to the MOE database.