0 14 cAMP-dependent camp-dependent JJ 15 25 regulation regulation NN 26 28 of of IN 29 42 proenkephalin proenkephalin NN 43 45 by by IN 46 50 JunD JunD NNP 51 54 and and CC 55 59 JunB JunB NNP 59 60 : : : 61 69 positive positive JJ 70 73 and and CC 74 82 negative negative JJ 83 90 effects effect NNS 91 93 of of IN 94 98 AP-1 ap-1 NN 99 107 proteins protein NNS 107 108 . . . 110 112 We we PRP 113 124 demonstrate demonstrate VBP 125 129 that that IN 130 134 JunD JunD NNP 134 135 , , , 136 137 a a DT 138 147 component component NN 148 150 of of IN 151 154 the the DT 155 159 AP-1 ap-1 NN 160 173 transcription transcription NN 174 180 factor factor NN 181 188 complex complex NN 188 189 , , , 190 199 activates activate VBZ 200 213 transcription transcription NN 214 216 of of IN 217 220 the the DT 221 226 human human JJ 227 240 proenkephalin proenkephalin NN 241 245 gene gene NN 246 248 in in IN 249 250 a a DT 251 258 fashion fashion NN 259 263 that that WDT 264 266 is be VBZ 267 277 completely completely RB 278 287 dependent dependent JJ 288 292 upon upon IN 293 296 the the DT 297 311 cAMP-dependent camp-dependent JJ 312 319 protein protein NN 320 326 kinase kinase NNP 326 327 , , , 328 335 protein protein NN 336 342 kinase kinase NNP 343 345 A. A. NNP 346 356 Activation Activation NNP 357 359 of of IN 360 373 proenkephalin proenkephalin NN 374 387 transcription transcription NN 388 390 by by IN 391 395 JunD JunD NNP 396 398 is be VBZ 399 408 dependent dependent JJ 409 413 upon upon IN 414 415 a a DT 416 426 previously previously RB 427 440 characterized characterize VBN 441 446 cAMP- camp- NN 446 447 , , , 448 455 phorbol phorbol NN 456 462 ester- ester- NN 462 463 , , , 464 467 and and CC 468 484 Ca(2+)-inducible ca(2+)-inducible JJ 485 493 enhancer enhancer NN 493 494 , , , 495 498 and and CC 499 503 JunD JunD NNP 504 506 is be VBZ 507 512 shown show VBN 513 515 to to TO 516 520 bind bind VB 521 524 the the DT 525 533 enhancer enhancer NN 534 536 as as IN 537 538 a a DT 539 548 homodimer homodimer NN 548 549 . . . 550 557 Another another DT 558 567 component component NN 568 570 of of IN 571 574 the the DT 575 579 AP-1 ap-1 NN 580 593 transcription transcription NN 594 601 complex complex NN 601 602 , , , 603 607 JunB JunB NNP 607 608 , , , 609 611 is be VBZ 612 617 shown show VBN 618 620 to to TO 621 628 inhibit inhibit VB 629 639 activation activation NN 640 648 mediated mediate VBN 649 651 by by IN 652 656 JunD JunD NNP 656 657 . . . 658 660 As as IN 661 662 a a DT 663 672 homodimer homodimer NN 673 677 JunB junb NN 678 680 is be VBZ 681 687 unable unable JJ 688 690 to to TO 691 695 bind bind VB 696 699 the the DT 700 708 enhancer enhancer NN 708 709 ; ; : 710 717 however however RB 718 720 in in IN 721 724 the the DT 725 733 presence presence NN 734 736 of of IN 737 742 c-Fos c-fos NN 742 743 , , , 744 757 high-affinity high-affinity JJ 758 765 binding binding NN 766 768 is be VBZ 769 777 observed observe VBN 777 778 . . . 779 790 Furthermore furthermore RB 790 791 , , , 792 796 JunD JunD NNP 797 799 is be VBZ 800 805 shown show VBN 806 808 to to TO 809 817 activate activate VB 818 831 transcription transcription NN 832 834 of of IN 835 840 genes gene NNS 841 847 linked link VBN 848 850 to to TO 851 855 both both CC 856 860 cAMP camp NN 861 864 and and CC 865 872 phorbol phorbol NN 873 878 ester ester NN 879 887 response response NN 888 896 elements element NNS 897 899 in in IN 900 901 a a DT 902 909 protein protein NN 910 916 kinase kinase NNP 917 928 A-dependent a-dependent JJ 929 936 fashion fashion NN 936 937 , , , 938 945 further further RB 946 954 blurring blur VBG 955 958 the the DT 959 970 distinction distinction NN 971 978 between between IN 979 984 these these DT 985 993 response response NN 994 1002 elements element NNS 1002 1003 . . . 1004 1009 These these DT 1010 1017 results result NNS 1018 1029 demonstrate demonstrate VBP 1030 1034 that that IN 1035 1038 the the DT 1039 1054 transcriptional transcriptional JJ 1055 1063 activity activity NN 1064 1066 of of IN 1067 1069 an an DT 1070 1082 AP-1-related ap-1-related JJ 1083 1090 protein protein NN 1091 1093 is be VBZ 1094 1103 regulated regulate VBN 1104 1106 by by IN 1107 1110 the the DT 1111 1125 cAMP-dependent camp-dependent JJ 1126 1142 second-messenger second-messenger NN 1143 1150 pathway pathway NN 1151 1154 and and CC 1155 1162 suggest suggest VBP 1163 1167 that that IN 1168 1172 JunD JunD NNP 1173 1176 and and CC 1177 1182 other other JJ 1183 1195 AP-1-related ap-1-related JJ 1196 1204 proteins protein NNS 1205 1208 may may MD 1209 1213 play play VB 1214 1216 an an DT 1217 1226 important important JJ 1227 1231 role role NN 1232 1234 in in IN 1235 1238 the the DT 1239 1249 regulation regulation NN 1250 1252 of of IN 1253 1257 gene gene NN 1258 1268 expression expression NN 1269 1271 by by IN 1272 1286 cAMP-dependent camp-dependent JJ 1287 1300 intracellular intracellular JJ 1301 1310 signaling signaling NN 1311 1319 pathways pathway NNS 1319 1320 . . .