HMGB2 stimulates GFI1B promoter activity through GATA-1 and Oct-1 binding to the GFI1B promoter in vitro. (A) Effects of HMGB2 on GFI1B promoter activity. Gfi-1B luciferase reporter construct was transfected into HeLa cells together with GATA-1, Oct-1, NF-Y, or HMGB2 expression vectors. Thirty hours after transfection, luciferase activity was evaluated. Individual transfection was normalized by measurement of Renilla luciferase activity (pRL-TK; Promega) and pGL2-luciferase activity. Experiments were performed with shControl-transduced (shControl) or shHMGB2-transduced (shHMGB2) cells. Results are means ± SD of 4 independent experiments; *P < .05 and ***P < .001. (B) Effects of mutations at GATA or Oct-1–putative binding sites at the GFI1B promoter. The construct bearing the GFI1B promoter sequence was mutated at the putative GATA-binding (site 1) or Oct-1–binding (sites 1 and 2) sites (mutations were indicated at the bottom of the figure by a cross on the schematic representation of the GFI1B promoter). Wild-type or mutated reporter constructs were transfected into HeLa cells together with GATA-1 alone or with GATA-1, Oct-1, and HMGB2 expression vectors. Luciferase activity was measured 30 hours after transfection. Results are means ± SD of 4 independent experiments; *P < .02 and **P < .003.