E2F1 functions as a repressor of the miR-223 gene. (A) Schematic representation of the different miR-223 promoter constructs used for reporter assays. (B-D) Luciferase reporter assays were performed in U937 cells using indicated reporters and E2F1 (B) and C/EBPα (C-D). Bars represent promoter activity for the corresponding vectors. Data are represented as mean ± SD from 3 independent experiments. *P < .05; **P < .01. (E-F) Chromatin derived from K562-C/EBPα-p42-ER cells (E) and AML blast cells (F) was immunoprecipitated with anti-E2F1, anti-C/EBPα, and immunoglobulin G antibodies. Recovered DNA was PCR amplified with primers specific for the E2F1 binding amplicon (oligo 1) and C/EBPα binding amplicon (oligo 2). (G) U937 cells were transfected with control or E2F1 vector. Total RNA was analyzed by quantitative RT-PCR with oligos for miR-223 (top) and with oligos for E2F1 (bottom). Data are represented as mean ± SD from 3 independent experiments. *P < .05; **P < .01.