Other problematic aspects are highlighted in an analysis of the 189 in situ entries from the Chemical Probe Portal (see 'Data-Driven Exploration of Selectivity and Off-Target Activities of Designated Chemical Probes . This indicated that only ~50% were still be considered as target-selective from activity data additional to that used during the assessments for portal inclusion. However, according to this report, for the other ~ 50%, the totality of public data casts doubt on the initial claims of selectivity. The persistence of problematic probes has been most recently highlighted in an experimental study (see 'Validation and Invalidation of Chemical Probes for the Human N-myristoyltransferases', 2019, PMID 31006618 and the 'In the Pipeline' commentary).