The A allele shows greater promoter functionality in response to IL-6. (A) The sequence of the Bβ chain gene from −623 to +9 was subcloned into the pGL2 basic luciferase vector, upstream from the luciferase gene. This portion of the Bβ chain gene contains all of the known proximal promoter elements required for induction of Bβ chain gene transcription: HNF-1 (hepatocyte nuclear factor-1), −79 to −91; C/EBP site (CAAT-enhancer binding protein site), −124 to −132; IL-6 RE (IL-6 response element), −137 to −142,16 and, in addition, the −455 F/S (−455 nucleotide and its proximal 5′ and 3′ flanking sites). (B) After stimulation of HepG2 cells transfected with either pGL2 vector only (control), pGL2/G-455 (guanine at −455 of the Bβ construct), and pGL2/A-455 (adenine at −455 of the Bβ construct) with IL-6 for 16 hours, the luciferase activity was quantitated and the fold increase in luciferase activity over basal level was statistically averaged for 10 independent experiments. The activity for the pGL2 vector only was 1.1- ± 0.2-fold, for pGL2/G-455 was 3.5- ± 1.2-fold, and for pGL2/A-455 was 4.8- ± 1.4-fold increase over basal level activity. Statistical analyses using a two-sample t-test for independent samples showed that luciferase activity under the control of the pGL2/A-455 construct was significantly different from pGL2/G-455 activity (P = .048).