0 3 AML AML NNP 4 7 and and CC 8 11 Ets Ets NNP 12 20 proteins protein NNS 21 29 regulate regulate VBP 30 33 the the DT 34 35 I i NN 36 42 alpha1 alpha1 NN 43 52 germ-line germ-line NN 53 61 promoter promoter NN 61 62 . . . 64 67 The the DT 68 82 immunoglobulin immunoglobulin NN 83 88 heavy heavy JJ 89 94 chain chain NN 95 96 ( ( ( 96 99 IgH IgH NNP 99 100 ) ) ) 101 106 class class NN 107 113 switch switch NN 114 127 recombination recombination NN 128 130 of of IN 131 132 B B NNP 133 144 lymphocytes lymphocyte NNS 145 159 preferentially preferentially RB 160 167 targets target VBZ 168 180 unrearranged unrearranged JJ 181 184 IgH igh JJ 185 190 genes gene NNS 191 195 that that WDT 196 200 have have VBP 201 208 already already RB 209 213 been be VBN 214 222 rendered render VBN 223 240 transcriptionally transcriptionally RB 241 247 active active JJ 247 248 . . . 249 262 Transcription transcription NN 263 265 of of IN 266 269 the the DT 270 279 germ-line germ-line NN 280 283 IgH igh NN 284 289 genes gene NNS 290 292 is be VBZ 293 303 controlled control VBN 304 306 by by IN 307 318 intervening intervene VBG 319 320 ( ( ( 320 321 I I PRP 321 322 ) ) ) 323 330 regions region NNS 331 339 upstream upstream RB 340 342 of of IN 343 348 their their PRP$ 349 355 switch switch NN 356 363 regions region NNS 363 364 . . . 365 368 The the DT 369 370 I i NN 371 377 alpha1 alpha1 NN 378 386 promoter promoter NN 387 396 activates activate VBZ 397 410 transcription transcription NN 411 413 of of IN 414 417 the the DT 418 423 human human JJ 424 433 germ-line germ-line NN 434 435 C C NNP 436 442 alpha1 alpha1 NN 443 447 gene gene NN 448 451 for for IN 452 456 IgA1 iga1 NN 457 460 and and CC 461 469 mediates mediate VBZ 470 473 the the DT 474 486 transforming transform VBG 487 493 growth growth NN 494 500 factor factor NN 501 502 ( ( ( 502 512 TGF)-beta1 tgf)-beta1 NN 513 527 responsiveness responsiveness NN 528 530 of of IN 531 535 this this DT 536 541 locus locus NN 541 542 . . . 543 547 Here here RB 548 550 we we PRP 551 555 show show VBP 556 560 that that IN 561 564 the the DT 565 566 I i NN 567 573 alpha1 alpha1 NN 574 582 promoter promoter NN 583 591 contains contain VBZ 592 599 several several JJ 600 607 binding bind VBG 608 613 sites site NNS 614 617 for for IN 618 621 the the DT 622 635 AML/PEBP2/CBF AML/PEBP2/CBF NNP 636 642 family family NN 643 645 of of IN 646 659 transcription transcription NN 660 667 factors factor NNS 668 671 and and CC 672 676 that that IN 677 680 AML AML NNP 681 684 and and CC 685 688 Ets Ets NNP 689 697 proteins protein NNS 698 701 are be VBP 702 707 major major JJ 708 718 regulators regulator NNS 719 721 of of IN 722 725 the the DT 726 731 basal basal JJ 732 735 and and CC 736 754 TGF-beta-inducible tgf-beta-inducible JJ 755 763 promoter promoter NN 764 772 activity activity NN 772 773 . . . 774 777 Our our PRP$ 778 782 data datum NNS 783 793 constitute constitute VBP 794 795 a a DT 796 804 starting starting JJ 805 810 point point NN 811 814 for for IN 815 822 studies study NNS 823 825 to to TO 826 835 elucidate elucidate VB 836 839 the the DT 840 849 molecular molecular JJ 850 859 mechanism mechanism NN 860 862 by by IN 863 868 which which WDT 869 877 TGF-beta TGF-beta NNP 878 887 regulates regulate VBZ 888 891 IgA IgA NNP 892 902 production production NN 902 903 . . .