0 13 Cell-specific cell-specific JJ 14 24 expression expression NN 25 27 of of IN 28 44 helix-loop-helix helix-loop-helix JJ 45 58 transcription transcription NN 59 66 factors factor NNS 67 74 encoded encode VBN 75 77 by by IN 78 81 the the DT 82 85 E2A E2A NNP 86 90 gene gene NN 90 91 . . . 93 96 The the DT 97 100 E2A E2A NNP 101 105 gene gene NN 106 113 encodes encode VBZ 114 127 transcription transcription NN 128 135 factors factor NNS 136 138 of of IN 139 142 the the DT 143 159 helix-loop-helix helix-loop-helix JJ 160 166 family family NN 167 171 that that WDT 172 175 are be VBP 176 186 implicated implicate VBN 187 189 in in IN 190 203 cell-specific cell-specific JJ 204 208 gene gene NN 209 219 expression expression NN 220 222 as as IN 223 227 part part NN 228 230 of of IN 231 238 dimeric dimeric JJ 239 248 complexes complex NNS 249 253 that that WDT 254 262 interact interact VBP 263 267 with with IN 268 269 E e NN 270 273 box box NN 274 282 enhancer enhancer NN 283 291 elements element NNS 291 292 . . . 293 295 It it PRP 296 299 has have VBZ 300 310 previously previously RB 311 315 been be VBN 316 321 shown show VBN 322 326 that that IN 327 338 transcripts transcript NNS 339 341 of of IN 342 345 the the DT 346 349 E2A E2A NNP 350 354 gene gene NN 355 358 can can MD 359 361 be be VB 362 370 detected detect VBN 371 373 in in IN 374 375 a a DT 376 380 wide wide JJ 381 386 range range NN 387 389 of of IN 390 394 cell cell NN 395 400 types type NNS 400 401 . . . 402 404 We we PRP 405 409 have have VBP 410 413 now now RB 414 422 examined examine VBN 423 433 expression expression NN 434 436 of of IN 437 440 the the DT 441 446 mouse mouse NN 447 450 E2A E2A NNP 451 455 gene gene NN 456 458 at at IN 459 462 the the DT 463 470 protein protein NN 471 476 level level NN 477 482 using use VBG 483 493 polyclonal polyclonal JJ 494 502 antisera antiserum NNS 503 511 directed direct VBN 512 519 against against IN 520 528 distinct distinct JJ 529 537 portions portion NNS 538 540 of of IN 541 544 the the DT 545 548 E2A E2A NNP 549 556 protein protein NN 557 559 to to TO 560 565 probe probe NN 566 571 blots blot NNS 572 574 of of IN 575 583 cellular cellular JJ 584 592 extracts extract NNS 592 593 . . . 594 595 A a DT 596 598 73 73 CD 599 602 kDa kda NN 603 610 protein protein NN 611 614 was be VBD 615 625 identified identify VBN 626 628 by by IN 629 633 this this DT 634 642 analysis analysis NN 642 643 : : : 644 648 this this DT 649 656 protein protein NN 657 659 is be VBZ 660 666 highly highly RB 667 675 enriched enrich VBN 676 678 in in IN 679 683 cell cell NN 684 689 lines line NNS 690 692 of of IN 693 694 B B NNP 695 703 lymphoid lymphoid JJ 704 710 origin origin NN 711 713 as as IN 714 722 compared compare VBN 723 725 to to TO 726 736 pancreatic pancreatic JJ 737 747 beta-cells beta-cell NNS 748 751 and and CC 752 762 fibroblast fibroblast NN 763 768 cells cell NNS 768 769 . . . 770 773 The the DT 774 783 detection detection NN 784 786 of of IN 787 791 this this DT 792 799 protein protein NN 800 811 selectively selectively RB 812 814 in in IN 815 823 extracts extract NNS 824 826 of of IN 827 835 lymphoid lymphoid JJ 836 841 cells cell NNS 842 852 correlates correlate VBZ 853 857 with with IN 858 861 the the DT 862 870 presence presence NN 871 873 of of IN 874 877 the the DT 878 879 E e NN 880 891 box-binding box-binding JJ 892 900 activity activity NN 901 910 LEF1/BCF1 lef1/bcf1 NN 911 913 in in IN 914 919 these these DT 920 925 cells cell NNS 925 926 ; ; : 927 931 this this DT 932 939 binding binding NN 940 948 activity activity NN 949 952 was be VBD 953 963 previously previously RB 964 969 shown show VBN 970 972 to to TO 973 975 be be VB 976 987 efficiently efficiently RB 988 998 recognized recognize VBN 999 1001 by by IN 1002 1011 antiserum antiserum NN 1012 1020 directed direct VBN 1021 1028 against against IN 1029 1032 E2A E2A NNP 1033 1037 gene gene NN 1038 1046 products product NNS 1046 1047 . . . 1048 1060 Transfection transfection NN 1061 1063 of of IN 1064 1069 cells cell NNS 1070 1074 with with IN 1075 1079 full full JJ 1080 1086 length length NN 1087 1090 E2A E2A NNP 1091 1095 cDNA cDNA NNP 1096 1101 leads lead VBZ 1102 1104 to to TO 1105 1115 appearance appearance NN 1116 1118 of of IN 1119 1126 protein protein NN 1127 1139 co-migrating co-migrate VBG 1140 1144 with with IN 1145 1148 the the DT 1149 1151 73 73 CD 1152 1155 kDa kda NN 1156 1163 protein protein NN 1164 1166 on on IN 1167 1170 SDS SDS NNP 1171 1174 gel gel NN 1175 1190 electrophoresis electrophoresis NN 1191 1194 and and CC 1195 1207 co-migrating co-migrate VBG 1208 1212 with with IN 1213 1222 LEF1/BCF1 lef1/bcf1 NN 1223 1225 on on IN 1226 1234 mobility mobility NN 1235 1240 shift shift NN 1241 1249 analysis analysis NN 1249 1250 . . . 1251 1254 Our our PRP$ 1255 1262 results result NNS 1263 1266 are be VBP 1267 1277 consistent consistent JJ 1278 1282 with with IN 1283 1286 the the DT 1287 1291 view view NN 1292 1296 that that IN 1297 1300 the the DT 1301 1312 DNA-binding dna-binding JJ 1313 1321 activity activity NN 1322 1331 LEF1/BCF1 lef1/bcf1 NN 1332 1334 is be VBZ 1335 1336 a a DT 1337 1346 homodimer homodimer NN 1347 1349 of of IN 1350 1353 E2A E2A NNP 1354 1362 proteins protein NNS 1362 1363 ; ; : 1364 1367 the the DT 1368 1377 selective selective JJ 1378 1388 appearance appearance NN 1389 1391 of of IN 1392 1396 this this DT 1397 1405 putative putative JJ 1406 1419 cell-specific cell-specific JJ 1420 1433 transcription transcription NN 1434 1440 factor factor NN 1441 1443 in in IN 1444 1445 B B NNP 1446 1454 lymphoid lymphoid JJ 1455 1460 cells cell NNS 1461 1466 seems seem VBZ 1467 1469 to to TO 1470 1472 be be VB 1473 1485 attributable attributable JJ 1485 1486 , , , 1487 1489 at at IN 1490 1495 least least JJS 1496 1498 in in IN 1499 1503 part part NN 1503 1504 , , , 1505 1507 to to TO 1508 1511 the the DT 1512 1520 elevated elevated JJ 1521 1524 E2A E2A NNP 1525 1532 protein protein NN 1533 1547 concentrations concentration NNS 1548 1550 in in IN 1551 1556 these these DT 1557 1562 cells cell NNS 1562 1563 . . .