Discussion Currently there exists only one electrophilic affmity label for glucocorticoid receptors. This is Dex-Mes, which displays irreversible antiglucocorticoid a~ tivity.'-~ J~ We have now prepared several new potential electrophilic affinity labels which could have irreversible agonist or antagonist activity. One of these, Dex-NCS (6 in (Scheme I) fulfills all of the requirements for being a new affinity label.(1) Dex-NCS has reasonable affinity for ...