0 6 GATA-1 gata-1 NN 7 10 and and CC 11 25 erythropoietin erythropoietin NN 26 35 cooperate cooperate VBP 36 38 to to TO 39 46 promote promote VB 47 56 erythroid erythroid JJ 57 61 cell cell NN 62 70 survival survival NN 71 73 by by IN 74 84 regulating regulate VBG 85 91 bcl-xL bcl-xl NN 92 102 expression expression NN 102 103 . . . 105 108 The the DT 109 122 transcription transcription NN 123 129 factor factor NN 130 136 GATA-1 gata-1 NN 137 139 is be VBZ 140 149 essential essential JJ 150 153 for for IN 154 160 normal normal JJ 161 175 erythropoiesis erythropoiesis NN 175 176 . . . 177 179 By by IN 180 189 examining examine VBG 190 192 in in IN 193 213 vitro-differentiated vitro-differentiated JJ 214 223 embryonic embryonic JJ 224 228 stem stem NN 229 234 cells cell NNS 234 235 , , , 236 238 we we PRP 239 245 showed show VBD 246 256 previously previously RB 257 261 that that IN 262 264 in in IN 265 268 the the DT 269 276 absence absence NN 277 279 of of IN 280 286 GATA-1 gata-1 NN 286 287 , , , 288 297 committed commit VBN 298 307 erythroid erythroid JJ 308 318 precursors precursor NNS 319 323 fail fail VBP 324 326 to to TO 327 335 complete complete VB 336 346 maturation maturation NN 347 350 and and CC 351 358 instead instead RB 359 366 undergo undergo VBP 367 376 apoptosis apoptosis NN 376 377 . . . 378 381 The the DT 382 392 mechanisms mechanism NNS 393 395 by by IN 396 401 which which WDT 402 408 GATA-1 gata-1 NN 409 417 controls control VBZ 418 422 cell cell NN 423 431 survival survival NN 432 435 are be VBP 436 443 unknown unknown JJ 443 444 . . . 445 449 Here here RB 450 452 we we PRP 453 459 report report VBP 460 464 that that IN 465 467 in in IN 468 477 erythroid erythroid JJ 478 483 cells cell NNS 483 484 , , , 485 491 GATA-1 gata-1 NN 492 500 strongly strongly RB 501 508 induces induce VBZ 509 512 the the DT 513 523 expression expression NN 524 526 of of IN 527 530 the the DT 531 545 anti-apoptotic anti-apoptotic JJ 546 553 protein protein NN 554 560 bcl-xL bcl-xl NN 560 561 , , , 562 565 but but CC 566 569 not not RB 570 573 the the DT 574 581 related relate VBN 582 590 proteins protein NNS 591 596 bcl-2 bcl-2 NN 597 600 and and CC 601 606 mcl-1 mcl-1 NN 606 607 . . . 608 618 Consistent consistent JJ 619 623 with with IN 624 625 a a DT 626 630 role role NN 631 634 for for IN 635 641 bcl-xL bcl-xl NN 642 644 in in IN 645 654 mediating mediate VBG 655 669 GATA-1-induced gata-1-induced JJ 670 679 erythroid erythroid JJ 680 684 cell cell NN 685 693 survival survival NN 693 694 , , , 695 697 in in IN 698 718 vitro-differentiated vitro-differentiated JJ 719 728 bcl-xL-/- bcl-xl-/- JJ 729 738 embryonic embryonic JJ 739 743 stem stem NN 744 749 cells cell NNS 750 754 fail fail VBP 755 757 to to TO 758 766 generate generate VB 767 773 viable viable JJ 774 780 mature mature JJ 781 791 definitive definitive JJ 792 801 erythroid erythroid JJ 802 807 cells cell NNS 807 808 , , , 809 810 a a DT 811 820 phenotype phenotype NN 821 831 resembling resemble VBG 832 836 that that DT 837 839 of of IN 840 846 GATA-1 gata-1 NN 847 851 gene gene NN 852 862 disruption disruption NN 862 863 . . . 864 866 In in IN 867 875 addition addition NN 875 876 , , , 877 879 we we PRP 880 884 show show VBP 885 889 that that IN 890 904 erythropoietin erythropoietin NN 904 905 , , , 906 911 which which WDT 912 914 is be VBZ 915 919 also also RB 920 928 required require VBN 929 932 for for IN 933 942 erythroid erythroid JJ 943 947 cell cell NN 948 956 survival survival NN 956 957 , , , 958 968 cooperates cooperate VBZ 969 973 with with IN 974 980 GATA-1 gata-1 NN 981 983 to to TO 984 993 stimulate stimulate VB 994 1000 bcl-xL bcl-xl NN 1001 1005 gene gene NN 1006 1016 expression expression NN 1017 1020 and and CC 1021 1023 to to TO 1024 1032 maintain maintain VB 1033 1042 erythroid erythroid JJ 1043 1047 cell cell NN 1048 1057 viability viability NN 1058 1064 during during IN 1065 1073 terminal terminal JJ 1074 1084 maturation maturation NN 1084 1085 . . . 1086 1094 Together together RB 1094 1095 , , , 1096 1099 our our PRP$ 1100 1104 data datum NNS 1105 1109 show show VBP 1110 1114 that that IN 1115 1121 bcl-xL bcl-xl NN 1122 1124 is be VBZ 1125 1134 essential essential JJ 1135 1138 for for IN 1139 1145 normal normal JJ 1146 1155 erythroid erythroid JJ 1156 1167 development development NN 1168 1171 and and CC 1172 1179 suggest suggest VBP 1180 1181 a a DT 1182 1192 regulatory regulatory JJ 1193 1202 hierarchy hierarchy NN 1203 1205 in in IN 1206 1211 which which WDT 1212 1218 bcl-xL bcl-xl NN 1219 1221 is be VBZ 1222 1223 a a DT 1224 1232 critical critical JJ 1233 1243 downstream downstream JJ 1244 1252 effector effector NN 1253 1255 of of IN 1256 1262 GATA-1 gata-1 NN 1263 1266 and and CC 1267 1290 erythropoietin-mediated erythropoietin-mediated JJ 1291 1298 signals signal NNS 1298 1299 . . .