FIGURE 5.

PBX1 requires PREP1 to regulate RNF6 transcription. A, PBX1, PREP1, MEIS1, and the core regulatory sequence of RNF6 were co-transfected into HEK293 cells. The RNF6 transcription level was analyzed by a Dual-Luciferase reporter assay system. The same lysates were applied to measure the RNF6 protein level using immunoblotting. B, PBX1 and PREP1 plasmids were co-transfected into HEK293 cells with increasing concentrations followed by measurement of RNF6 transcription in a Dual-Luciferase reporter assay system. C, PBX1, PREP1, and MEIS1 plasmids were co-transfected in HeLa cells, and cell lysates were then prepared for immunoblotting against specific proteins as indicated. D, statistical analysis of C. E, K562 cells were transfected with PREP1 siRNAs for 72 h, and then whole cell lysates and total RNA were extracted for immunoblotting and RT-PCR as indicated. *, p < 0.05; **, p < 0.01; ***, p < 0.001, as compared with control. Error bars indicate ± S.E.