0 10 Regulation regulation NN 11 13 of of IN 14 17 the the DT 18 29 Ets-related ets-related JJ 30 43 transcription transcription NN 44 50 factor factor NN 51 56 Elf-1 elf-1 NN 57 59 by by IN 60 67 binding bind VBG 68 70 to to TO 71 74 the the DT 75 89 retinoblastoma retinoblastoma NN 90 97 protein protein NN 97 98 . . . 100 103 The the DT 104 118 retinoblastoma retinoblastoma NN 119 123 gene gene NN 124 131 product product NN 132 133 ( ( ( 133 135 Rb Rb NNP 135 136 ) ) ) 137 139 is be VBZ 140 141 a a DT 142 149 nuclear nuclear JJ 150 164 phosphoprotein phosphoprotein NN 165 169 that that WDT 170 179 regulates regulate VBZ 180 184 cell cell NN 185 190 cycle cycle NN 191 202 progression progression NN 202 203 . . . 204 209 Elf-1 Elf-1 NNP 210 212 is be VBZ 213 214 a a DT 215 232 lymphoid-specific lymphoid-specific JJ 233 236 Ets Ets NNP 237 250 transcription transcription NN 251 257 factor factor NN 258 262 that that WDT 263 272 regulates regulate VBZ 273 282 inducible inducible JJ 283 287 gene gene NN 288 298 expression expression NN 299 305 during during IN 306 307 T t NN 308 312 cell cell NN 313 323 activation activation NN 323 324 . . . 325 327 In in IN 328 332 this this DT 333 339 report report NN 339 340 , , , 341 343 it it PRP 344 346 is be VBZ 347 359 demonstrated demonstrate VBN 360 364 that that IN 365 370 Elf-1 elf-1 NN 371 379 contains contain VBZ 380 381 a a DT 382 390 sequence sequence NN 391 396 motif motif NN 397 401 that that WDT 402 404 is be VBZ 405 411 highly highly RB 412 419 related related JJ 420 422 to to TO 423 426 the the DT 427 429 Rb Rb NNP 430 437 binding binding NN 438 443 sites site NNS 444 446 of of IN 447 454 several several JJ 455 460 viral viral JJ 461 473 oncoproteins oncoprotein NNS 474 477 and and CC 478 483 binds bind VBZ 484 486 to to TO 487 490 the the DT 491 497 pocket pocket NN 498 504 region region NN 505 507 of of IN 508 510 Rb Rb NNP 511 515 both both CC 516 518 in in FW 519 524 vitro vitro FW 525 528 and and CC 529 531 in in FW 532 536 vivo vivo FW 536 537 . . . 538 543 Elf-1 elf-1 NN 544 549 binds bind VBZ 550 561 exclusively exclusively RB 562 564 to to TO 565 568 the the DT 569 588 underphosphorylated underphosphorylated JJ 589 593 form form NN 594 596 of of IN 597 599 Rb Rb NNP 600 603 and and CC 604 609 fails fail VBZ 610 612 to to TO 613 617 bind bind VB 618 620 to to TO 621 623 Rb Rb NNP 624 631 mutants mutant NNS 632 639 derived derive VBN 640 644 from from IN 645 653 patients patient NNS 654 658 with with IN 659 673 retinoblastoma retinoblastoma NN 673 674 . . . 675 697 Co-immunoprecipitation Co-immunoprecipitation NNP 698 709 experiments experiment NNS 710 722 demonstrated demonstrate VBD 723 725 an an DT 726 737 association association NN 738 745 between between IN 746 751 Elf-1 Elf-1 NNP 752 755 and and CC 756 758 Rb Rb NNP 759 761 in in IN 762 769 resting rest VBG 770 776 normal normal JJ 777 782 human human JJ 783 784 T t NN 785 790 cells cell NNS 790 791 . . . 792 797 After after IN 798 799 T t NN 800 804 cell cell NN 805 815 activation activation NN 815 816 , , , 817 820 the the DT 821 836 phosphorylation phosphorylation NN 837 839 of of IN 840 842 Rb Rb NNP 843 850 results result VBZ 851 853 in in IN 854 857 the the DT 858 865 release release NN 866 868 of of IN 869 874 Elf-1 Elf-1 NNP 874 875 , , , 876 881 which which WDT 882 884 is be VBZ 885 895 correlated correlate VBN 896 906 temporally temporally RB 907 911 with with IN 912 915 the the DT 916 926 activation activation NN 927 929 of of IN 930 944 Elf-1-mediated elf-1-mediated JJ 945 958 transcription transcription NN 958 959 . . . 960 974 Overexpression overexpression NN 975 977 of of IN 978 979 a a DT 980 1005 phosphorylation-defective phosphorylation-defective JJ 1006 1010 form form NN 1011 1013 of of IN 1014 1016 Rb Rb NNP 1017 1026 inhibited inhibit VBD 1027 1042 Elf-1-dependent elf-1-dependent JJ 1043 1056 transcription transcription NN 1057 1063 during during IN 1064 1065 T t NN 1066 1070 cell cell NN 1071 1081 activation activation NN 1081 1082 . . . 1083 1088 These these DT 1089 1096 results result NNS 1097 1108 demonstrate demonstrate VBP 1109 1113 that that IN 1114 1116 Rb Rb NNP 1117 1126 interacts interact VBZ 1127 1139 specifically specifically RB 1140 1144 with with IN 1145 1146 a a DT 1147 1165 lineage-restricted lineage-restricted JJ 1166 1169 Ets Ets NNP 1170 1183 transcription transcription NN 1184 1190 factor factor NN 1190 1191 . . . 1192 1196 This this DT 1197 1206 regulated regulated JJ 1207 1218 interaction interaction NN 1219 1222 may may MD 1223 1225 be be VB 1226 1235 important important JJ 1236 1239 for for IN 1240 1243 the the DT 1244 1256 coordination coordination NN 1257 1259 of of IN 1260 1276 lineage-specific lineage-specific JJ 1277 1285 effector effector NN 1286 1295 functions function NNS 1296 1300 such such JJ 1301 1303 as as IN 1304 1314 lymphokine lymphokine NN 1315 1325 production production NN 1326 1330 with with IN 1331 1335 cell cell NN 1336 1341 cycle cycle NN 1342 1353 progression progression NN 1354 1356 in in IN 1357 1366 activated activate VBN 1367 1368 T t NN 1369 1374 cells cell NNS 1374 1375 . . .