0 16 Characterization characterization NN 17 19 of of IN 20 30 peripheral peripheral JJ 31 36 blood blood NN 37 50 T-lymphocytes t-lymphocyte NNS 51 61 transduced transduce VBN 62 66 with with IN 67 73 HTLV-I HTLV-I NNP 74 77 Tax Tax NNP 78 85 mutants mutant NNS 86 90 with with IN 91 100 different different JJ 101 117 trans-activating trans-activating JJ 118 128 phenotypes phenotype NNS 128 129 . . . 131 135 Tax1 Tax1 NNP 135 136 , , , 137 138 a a DT 139 154 transcriptional transcriptional JJ 155 170 trans-activator trans-activator NN 171 173 of of IN 174 177 the the DT 178 183 Human human JJ 184 190 T-cell T-cell NNP 191 199 leukemia leukemia NN 200 205 virus virus NN 206 210 type type NN 211 212 I i CD 213 214 ( ( ( 214 220 HTLV-I HTLV-I NNP 220 221 ) ) ) 221 222 , , , 223 230 induces induce VBZ 231 234 the the DT 235 245 expression expression NN 246 248 of of IN 249 253 many many JJ 254 262 cellular cellular JJ 263 268 genes gene NNS 269 276 through through IN 277 288 interaction interaction NN 289 293 with with IN 294 296 at at IN 297 302 least least JJS 303 308 three three CD 309 317 distinct distinct JJ 318 326 cellular cellular JJ 327 340 transcription transcription NN 341 348 factors factor NNS 348 349 ; ; : 350 358 CREB/ATF CREB/ATF NNP 358 359 , , , 360 369 NF-kappaB NF-kappaB NNP 369 370 , , , 371 374 and and CC 375 378 SRF SRF NNP 378 379 . . . 380 384 This this DT 385 397 Tax1-induced tax1-induced JJ 398 408 activation activation NN 409 411 of of IN 412 420 cellular cellular JJ 421 426 genes gene NNS 427 429 is be VBZ 430 440 considered consider VBN 441 443 to to TO 444 446 be be VB 447 448 a a DT 449 457 critical critical JJ 458 463 event event NN 464 466 in in IN 467 473 T-cell t-cell NN 474 488 transformation transformation NN 489 491 by by IN 492 498 HTLV-I HTLV-I NNP 498 499 . . . 500 502 To to TO 503 512 elucidate elucidate VB 513 516 the the DT 517 521 role role NN 522 524 of of IN 525 529 each each DT 530 544 Tax1-inducible tax1-inducible JJ 545 560 transcriptional transcriptional JJ 561 568 pathway pathway NN 569 571 in in IN 572 578 T-cell t-cell NN 579 593 transformation transformation NN 593 594 , , , 595 597 we we PRP 598 608 introduced introduce VBD 609 613 Tax1 tax1 NN 614 621 mutants mutant NNS 622 626 with with IN 627 636 different different JJ 637 653 trans-activating trans-activating JJ 654 664 phenotypes phenotype NNS 665 669 into into IN 670 680 peripheral peripheral JJ 681 686 blood blood NN 687 698 lymphocytes lymphocyte NNS 699 700 ( ( ( 700 703 PBL PBL NNP 703 704 ) ) ) 705 707 by by IN 708 718 retroviral retroviral JJ 719 726 vectors vector NNS 726 727 . . . 728 736 Analysis Analysis NNP 737 739 of of IN 740 745 these these DT 746 750 PBLs PBL NNPS 751 759 revealed reveal VBD 760 764 that that IN 765 775 activation activation NN 776 778 of of IN 779 782 the the DT 783 792 NF-kappaB NF-kappaB NNP 793 800 pathway pathway NN 801 803 is be VBZ 804 814 sufficient sufficient JJ 815 817 to to TO 818 825 promote promote VB 826 829 the the DT 830 836 growth growth NN 837 845 response response NN 846 848 to to TO 849 853 IL-2 il-2 NN 853 854 . . . 855 862 However however RB 862 863 , , , 864 867 for for IN 868 871 the the DT 872 878 clonal clonal JJ 879 888 expansion expansion NN 889 891 of of IN 892 896 CD4+ cd4+ JJ 897 904 T-cells T-cell NNP 904 905 , , , 906 911 which which WDT 912 914 is be VBZ 915 916 a a DT 917 931 characteristic characteristic JJ 932 938 result result NN 939 941 of of IN 942 948 HTLV-I HTLV-I NNP 949 958 infection infection NN 958 959 , , , 960 970 activation activation NN 971 973 of of IN 974 977 the the DT 978 986 CREB/ATF CREB/ATF NNP 987 990 and and CC 991 994 SRF SRF NNP 995 1003 pathways pathway NNS 1004 1006 is be VBZ 1007 1011 also also RB 1012 1020 required require VBN 1020 1021 . . .