A GR monomer is not sufficient to mediate the antiapoptotic effect of GCs in T cells. DC27.1 T cells (A), primary murine day-5 T cells (B), and primary human day-6 T cells (C) were (re-) stimulated by anti-CD3 antibody in the presence or absence of 10^-7 M Dex and/or 5 μM RU486 for 18 hours. Apoptosis was determined by FSC/SSC-FACS analysis. Results are for at least 4 independent experiments. (D) Southern blot analysis of the GR gene locus. Thymocytes, peripheral splenic T cells, and cells from liver, kidney, and brain were tested for successful recombination in GR^loxP/loxP mice with or without expression of Cre-recombinase under the control of the lck-promoter (GR^lckCre). Upper band: loxP-flanked locus (floxed); lower band: recombined locus (null). (E) Day-5 T cells from GR^lckCre, GR^dim, or control mice (GR^loxP/loxP) were restimulated by anti-CD3 antibody for 8 hours in the presence or absence of 10^-7 M Dex. CD95L protein expression on the cell surface was assayed by FACS analysis (n = 4). (F) Same as in panel E, but determination of apoptosis after 18 hours of restimulation (n = 3). Error bars are mean ± SEM.