0 9 NF-kappaB NF-kappaB NNP 10 19 functions function VBZ 20 22 as as IN 23 27 both both CC 28 29 a a DT 30 42 proapoptotic proapoptotic JJ 43 46 and and CC 47 60 antiapoptotic antiapoptotic JJ 61 71 regulatory regulatory JJ 72 78 factor factor NN 79 85 within within IN 86 87 a a DT 88 94 single single JJ 95 99 cell cell NN 100 104 type type NN 104 105 . . . 107 115 Recently recently RB 116 125 NF-kappaB NF-kappaB NNP 126 129 has have VBZ 130 134 been be VBN 135 140 shown show VBN 141 143 to to TO 144 148 have have VB 149 153 both both CC 154 166 proapoptotic proapoptotic JJ 167 170 and and CC 171 184 antiapoptotic antiapoptotic JJ 185 194 functions function NNS 194 195 . . . 196 198 In in IN 199 200 T t NN 201 205 cell cell NN 206 216 hybridomas hybridoma NNS 216 217 , , , 218 222 both both CC 223 224 T t NN 225 229 cell cell NN 230 240 activators activator NNS 241 244 and and CC 245 260 glucocorticoids glucocorticoid NNS 261 267 induce induce VBP 268 277 apoptosis apoptosis NN 277 278 . . . 279 283 Here here RB 284 286 we we PRP 287 291 show show VBP 292 296 that that IN 297 305 blockade blockade NN 306 308 of of IN 309 318 NF-kappaB NF-kappaB NNP 319 327 activity activity NN 327 328 , , , 329 334 using use VBG 335 336 a a DT 337 345 dominant dominant JJ 346 354 negative negative JJ 355 367 IkappaBalpha IkappaBalpha NNP 367 368 , , , 369 372 has have VBZ 373 381 opposite opposite JJ 382 389 effects effect NNS 390 392 on on IN 393 398 these these DT 399 402 two two CD 403 412 apoptotic apoptotic JJ 413 420 signals signal NNS 420 421 . . . 422 431 Treatment Treatment NNP 432 436 with with IN 437 440 PMA PMA NNP 441 445 plus plus CC 446 455 ionomycin ionomycin NN 456 457 ( ( ( 457 460 P/I P/I NNP 460 461 ) ) ) 462 469 results result VBZ 470 472 in in IN 473 476 the the DT 477 489 upregulation upregulation NN 490 492 of of IN 493 496 Fas Fas NNP 497 503 Ligand Ligand NNP 504 505 ( ( ( 505 509 FasL FasL NNP 509 510 ) ) ) 511 514 and and CC 515 524 induction induction NN 525 527 of of IN 528 537 apoptosis apoptosis NN 537 538 . . . 539 549 Inhibition Inhibition NNP 550 552 of of IN 553 562 NF-kappaB NF-kappaB NNP 563 571 activity activity NN 572 580 inhibits inhibit VBZ 581 584 the the DT 585 588 P/I P/I NNP 589 597 mediated mediate VBD 598 607 induction induction NN 608 610 of of IN 611 615 FasL FasL NNP 616 620 mRNA mRNA NNP 621 624 and and CC 625 634 decreases decrease VBZ 635 638 the the DT 639 644 level level NN 645 647 of of IN 648 657 apoptosis apoptosis NN 658 660 in in IN 661 666 these these DT 667 675 cultures culture NNS 675 676 , , , 677 681 thus thus RB 682 694 establishing establish VBG 695 704 NF-kappaB nf-kappab NN 705 707 as as IN 708 709 a a DT 710 722 proapoptotic proapoptotic JJ 723 729 factor factor NN 730 732 in in IN 733 737 this this DT 738 745 context context NN 745 746 . . . 747 757 Conversely conversely RB 757 758 , , , 759 769 inhibition inhibition NN 770 772 of of IN 773 782 NF-kappaB NF-kappaB NNP 783 790 confers confer VBZ 791 792 a a DT 793 800 tenfold tenfold JJ 801 809 increase increase NN 810 812 in in IN 813 827 glucocorticoid glucocorticoid NN 828 836 mediated mediated JJ 837 846 apoptosis apoptosis NN 846 847 , , , 848 860 establishing establish VBG 861 865 that that IN 866 875 NF-kappaB NF-kappaB NNP 876 880 also also RB 881 890 functions function VBZ 891 893 as as IN 894 896 an an DT 897 910 antiapoptotic antiapoptotic JJ 911 917 factor factor NN 917 918 . . . 919 921 We we PRP 922 930 conclude conclude VBP 931 935 that that IN 936 945 NF-kappaB NF-kappaB NNP 946 948 is be VBZ 949 950 a a DT 951 968 context-dependent context-dependent JJ 969 978 apoptosis apoptosis NN 979 988 regulator regulator NN 988 989 . . . 990 993 Our our PRP$ 994 998 data datum NNS 999 1007 suggests suggest VBZ 1008 1012 that that IN 1013 1022 NF-kappaB NF-kappaB NNP 1023 1026 may may MD 1027 1035 function function VB 1036 1038 as as IN 1039 1041 an an DT 1042 1055 antiapoptotic antiapoptotic JJ 1056 1062 factor factor NN 1063 1065 in in IN 1066 1076 thymocytes thymocyte NNS 1077 1082 while while IN 1083 1094 functioning function VBG 1095 1097 as as IN 1098 1099 a a DT 1100 1112 proapoptotic proapoptotic JJ 1113 1119 factor factor NN 1120 1122 in in IN 1123 1129 mature mature JJ 1130 1140 peripheral peripheral JJ 1141 1142 T t NN 1143 1148 cells cell NNS 1148 1149 . . .