0 4 Does do VBZ 5 15 activation activation NN 16 18 of of IN 19 22 the the DT 23 27 TAL1 tal1 NN 28 32 gene gene NN 33 38 occur occur VBP 39 41 in in IN 42 43 a a DT 44 52 majority majority NN 53 55 of of IN 56 64 patients patient NNS 65 69 with with IN 70 76 T-cell t-cell NN 77 82 acute acute JJ 83 96 lymphoblastic lymphoblastic JJ 97 105 leukemia leukemia NN 105 106 ? ? . 107 108 A a DT 109 118 pediatric pediatric JJ 119 127 oncology oncology NN 128 133 group group NN 134 139 study study NN 139 140 . . . 142 148 Almost almost RB 149 151 25 25 CD 151 152 % % NN 153 155 of of IN 156 164 patients patient NNS 165 169 with with IN 170 176 T-cell t-cell NN 177 182 acute acute JJ 183 196 lymphoblastic lymphoblastic JJ 197 205 leukemia leukemia NN 206 207 ( ( ( 207 212 T-ALL T-ALL NNP 212 213 ) ) ) 214 218 have have VBP 219 233 tumor-specific tumor-specific JJ 234 248 rearrangements rearrangement NNS 249 251 of of IN 252 255 the the DT 256 260 TAL1 tal1 NN 261 265 gene gene NN 265 266 . . . 267 275 Although although IN 276 280 TAL1 tal1 NN 281 291 expression expression NN 292 295 has have VBZ 296 299 not not RB 300 304 been be VBN 305 313 observed observe VBN 314 316 in in IN 317 323 normal normal JJ 324 335 lymphocytes lymphocyte NNS 335 336 , , , 337 341 TAL1 tal1 NN 342 346 gene gene NN 347 355 products product NNS 356 359 are be VBP 360 367 readily readily RB 368 376 detected detect VBN 377 379 in in IN 380 388 leukemic leukemic JJ 389 394 cells cell NNS 395 399 that that WDT 400 406 harbor harbor VBP 407 408 a a DT 409 419 rearranged rearrange VBN 420 424 TAL1 tal1 NN 425 431 allele allele NN 431 432 . . . 433 438 Hence hence RB 438 439 , , , 440 442 it it PRP 443 446 has have VBZ 447 451 been be VBN 452 460 proposed propose VBN 461 465 that that IN 466 473 ectopic ectopic JJ 474 484 expression expression NN 485 487 of of IN 488 492 TAL1 TAL1 NNP 493 501 promotes promote VBZ 502 505 the the DT 506 517 development development NN 518 520 of of IN 521 526 T-ALL T-ALL NNP 526 527 . . . 528 530 In in IN 531 535 this this DT 536 542 report report NN 542 543 , , , 544 546 we we PRP 547 551 show show VBP 552 556 that that IN 557 561 TAL1 tal1 NN 562 564 is be VBZ 565 574 expressed express VBN 575 577 in in IN 578 581 the the DT 582 590 leukemic leukemic JJ 591 596 cells cell NNS 597 599 of of IN 600 604 most most JJS 605 613 patients patient NNS 614 618 with with IN 619 624 T-ALL T-ALL NNP 624 625 , , , 626 635 including include VBG 636 640 many many JJ 641 645 that that WDT 646 648 do do VBP 649 652 not not RB 653 660 display display VB 661 663 an an DT 664 672 apparent apparent JJ 673 677 TAL1 tal1 NN 678 682 gene gene NN 683 693 alteration alteration NN 693 694 . . . 695 696 A a DT 697 708 polymorphic polymorphic JJ 709 721 dinucleotide dinucleotide NN 722 728 repeat repeat NN 729 731 in in IN 732 735 the the DT 736 747 transcribed transcribe VBN 748 757 sequences sequence NNS 758 760 of of IN 761 765 TAL1 TAL1 NNP 766 769 was be VBD 770 774 used use VBN 775 777 to to TO 778 787 determine determine VB 788 791 the the DT 792 798 allele allele NN 799 810 specificity specificity NN 811 813 of of IN 814 818 TAL1 tal1 NN 819 832 transcription transcription NN 833 835 in in IN 836 843 primary primary JJ 844 849 T-ALL t-all NN 850 855 cells cell NNS 855 856 . . . 857 868 Monoallelic monoallelic JJ 869 879 expression expression NN 880 882 of of IN 883 887 TAL1 TAL1 NNP 888 891 was be VBD 892 900 observed observe VBN 901 903 in in IN 904 907 the the DT 908 916 leukemic leukemic JJ 917 922 cells cell NNS 923 925 of of IN 926 929 all all DT 930 938 patients patient NNS 939 940 ( ( ( 940 941 8 8 CD 942 944 of of IN 945 946 8 8 CD 946 947 ) ) ) 948 955 bearing bear VBG 956 957 a a DT 958 962 TAL1 tal1 NN 963 967 gene gene NN 968 981 rearrangement rearrangement NN 981 982 . . . 983 985 In in IN 986 989 the the DT 990 998 leukemic leukemic JJ 999 1004 cells cell NNS 1005 1007 of of IN 1008 1016 patients patient NNS 1017 1024 without without IN 1025 1035 detectable detectable JJ 1036 1040 TAL1 tal1 NN 1041 1055 rearrangements rearrangement NNS 1055 1056 , , , 1057 1061 TAL1 tal1 NN 1062 1075 transcription transcription NN 1076 1084 occurred occur VBD 1085 1087 in in IN 1088 1094 either either CC 1095 1096 a a DT 1097 1108 monoallelic monoallelic JJ 1109 1110 ( ( ( 1110 1111 3 3 CD 1112 1114 of of IN 1115 1116 7 7 CD 1117 1125 patients patient NNS 1125 1126 ) ) ) 1127 1129 or or CC 1130 1131 a a DT 1132 1141 biallelic biallelic JJ 1142 1143 ( ( ( 1143 1144 4 4 CD 1145 1147 of of IN 1148 1149 7 7 CD 1150 1158 patients patient NNS 1158 1159 ) ) ) 1160 1167 fashion fashion NN 1167 1168 . . . 1169 1173 Thus thus RB 1173 1174 , , , 1175 1179 TAL1 tal1 NN 1180 1190 activation activation NN 1191 1193 in in IN 1194 1199 these these DT 1200 1208 patients patient NNS 1209 1212 may may MD 1213 1219 result result VB 1220 1224 from from IN 1225 1231 subtle subtle JJ 1232 1243 alterations alteration NNS 1244 1246 in in IN 1247 1257 cis-acting cis-acting JJ 1258 1268 regulatory regulatory JJ 1269 1278 sequences sequence NNS 1279 1280 ( ( ( 1280 1289 affecting affect VBG 1290 1300 expression expression NN 1301 1303 of of IN 1304 1305 a a DT 1306 1312 single single JJ 1313 1317 TAL1 tal1 NN 1318 1324 allele allele NN 1324 1325 ) ) ) 1326 1328 or or CC 1329 1336 changes change NNS 1337 1339 in in IN 1340 1352 trans-acting trans-acting JJ 1353 1360 factors factor NNS 1361 1365 that that WDT 1366 1373 control control VBP 1374 1378 TAL1 tal1 NN 1379 1392 transcription transcription NN 1393 1394 ( ( ( 1394 1403 affecting affect VBG 1404 1414 expression expression NN 1415 1417 of of IN 1418 1422 both both DT 1423 1427 TAL1 tal1 NN 1428 1435 alleles allele NNS 1435 1436 ) ) ) 1436 1437 . . .