Merget et al's dataset 14 , consisting of 260,757 activity data points of 47,774 compounds measured on 241 targets was considered of high quality, except for activity values originating from ChEMBL22, which were disregarded. Data originating from the Published Kinase Inhibitor Set (PKIS) of GlaxoSmithKline (doi:10.1038/nbt.3374) with activity values of 5 log units were considered as censored and as such reclassified as low quality data. Swiss-Prot sequences were retrieved using HUGO Gene Nomenclature Committee (HGNC) identifiers , a few of which were manually fixed (Supplementary Table ). Protein classifications were retrieved from ChEMBL29.