In human T cells mifepristone antagonizes glucocorticoid non-genomic rapid responses in terms of Na+/H+-exchange 1 activity, but not ezrin/radixin/moesin phosphorylation

GCs stimulate a rapid non-genomic cp-ERM response in cells within 5 min. RU486 antagonized the GC-induced rapid decrease in NHE1 activity, and arrested PHA-stimulated T cells at G0/G1 phase but had no effect on the rapid increase in cp-ERM, which persisted for 24 h. However, the cp-ERM response was blocked by staurosporine in both resting and GC stimulated cells. The results of RU486 antagonized the GC induced rapid decrease in NHE1 ion transport activity, but not the increase cp-ERM. This suggests that RU486 in T cells exerts its antagonistic effects at NHE1 containing plasma membrane sites and not where cp-ERM links lipid rafts to cortical cytoskeletons.