Transcriptional activity of β-chain promoter was downregulated by FOG-1 expression in mast cells. Five micrograms of each reporter plasmid was introduced into PT18 cells with or without 3 μg of expression plasmid. The ratio of luciferase activity of each construct in the absence of expression plasmid to that of pGL3-Basic was represented as relative luciferase activity. □ indicates without expression plasmid; ▪, with mock expression plasmid; and ▦, with FOG-1 expression plasmid.