4. The identification and provision of the crucial control compounds lag behind probe availability. Notably, a recent analysis of negative controls extols the council of perfection in that a quartet of compounds is needed to maximise interpretation (i.e. two probes of different chemotypes and two negative controls, also matched as different chemotypes). 5. There are many selective and potent compounds appearing in the recent medicinal chemistry and chemical biology literature that, while not officially yet declared in probe sources, include sufficient characterisation for useful probe criteria scoring. However, the rate of data extraction from these publications and flow into databases remains slow. 6. We are considering how to address the mismatched and missing probes in PubChem but we need to iterate with the originating sources in the first instance.