Résumé
The glucocorticoid receptor (GR) belongs to the family of steroid receptors (SRs). These receptors regulate a vastselection of cell-, tissue-, and organism biology, and are also targets of endocrine disrupting chemicals warrantingdesign and validation of in vitro assays. Here we report a “blinded” ring trial of an in vitro cell-based GRtransactivation assay with four involved laboratories. The laboratories set up the assay and tested 34 selectedchemicals with remarkably good concordance. There was agreement between all laboratories for the classificationof activity in 97 % of the cases, and three or more laboratories were always in agreement. The withinlaboratory concordance was very high (99.6 %) with only one of all 272 triplicates deviating. The assay was,thus, deemed easily transferable and reproducible within and between laboratories, since they would arrive atthe same qualitative results. Furthermore, for the chemicals with solid data regarding GR activation or inhibition,the laboratories arrived at the expected conclusion in all cases. Overall, the transfer and validation were successful,and the method is under evaluation to become an OECD test guideline. The method is expected tobecome valuable in tiered approaches for assessing chemicals or environmental samples together with othersimilar methods.