Association of nuclear proteins with the repressor elements in the FR-β promoter in relation to cell type and ATRA or TPA treatment by EMSA. (A) Nuclear protein binding to the repressor element in the FR-β promoter in peripheral blood monocytes and neutrophils. Lanes 1 to 4, 30 000 cpm ³²P-labeled FR-β probe (– 368 nt to – 328 nt); lane 2, 10 μg nuclear extract from monocytes; lane 3, 10 μg nuclear extract from neutrophils; and lane 4, 5 μg nuclear extract from KG-1 cells. (B) Nuclear protein binding to the repressor element in the FR-β promoter in peripheral blood monocytes and neutrophils. Lanes 1 to 4, 30 000 cpm ³²P-labeled FR-β probe (– 338 nt to – 308 nt); lane 2, 10 μg nuclear extract from monocytes; lane 3, 10 μg nuclear extract from neutrophils; lane 4, 5 μg nuclear extract from KG-1 cells. (C) Binding of nuclear protein from KG-1 cells treated with ATRA or TPA to repressor elements in the FR-β promoter. KG-1 cells were treated with ATRA (1 μM) or TPA (0.05 μM) for 5 days and nuclear extracts were made as described in “Materials and methods.” Lanes 1 to 4, 30 000 cpm ³²P-labeled probe (– 368 nt to – 328 nt); lanes 5 to 8, 30 000 cpm ³²P-labeled probe (– 338 nt to – 308 nt); lanes 2 and 6, 5 μg nuclear extract from KG-1 cells without treatment; lanes 3 and 7, 5 μg nuclear extract from KG-1 cells treated with ATRA; and lanes 4 and 8, 5 μg nuclear extract from KG-1 cells treated with TPA.