The synergistic activation of the PF4 promoter by GATA-1, ETS-1, and the PBX/MEIS complex. (A) The plasmids for the expression of ETS-1 and GATA-1 were transfected into HepG2 cells with the plasmids for MEIS1, PBX1B, and PBX2 expression. Transcriptional activities were evaluated with PF4luc or PF4mut plasmids. The expressions of all transcription factors and GAPDH (as a control) were confirmed by Western blotting (bottom panel). (B) PF4luc or PF4mut reporter-plasmids were transfected into HEL cells, and transcriptional activities were evaluated. Error bars indicate SDs.