Another key aspect of PubChem is the subsumation of many valuable individual collections within its 681 Data Sources. For example, GtoPdb ChEMBL, BindingDB and SureChEMBL are joined by DrugBank, DrugCentral, ChEBI and many other curated sources with ADEV utility. However, this presents a challenge in that, while complementary in aggregate (i. After exploration of chemical space, the second essential cross-check is against public bioassay data. This can certainly be done in ChEMBL but in terms of efficiency PubChem can be queried directly. As can be seen in Fig , at 1.34 million assays this only has ~ 0.25 million that ChEMBL does not (most from MLPCN screening centres as described in the probe section above) because the latter is the by far the major submitter of activity results to the former. Notwithstanding, any matches between ADEV compound structures (including their similarity neighbours and scaffold matches) need careful inspection. This is not just to check for positive BioAssays against the indicated protein targets but also inactive test results.