Transcriptional regulation by Twist1 in 10.5-dpc IACs. (A) ChIP was performed in c-Kit⁺CD31⁺CD34⁺ cells from 10.5-dpc AGM of WT mice, and real-time PCR was employed to amplify promoter regions of Myb or Gata2. (B) Myb promoter activation by Twist1. 293Ta cells were cotransfected with Myb promoter- and mutant Myb promoter-containing luciferase plasmids plus a Twist1 expression plasmid, and luciferase activity was analyzed as fold change, calculated as the signal of Twist-Myb or Twist-mutant Myb promoters divided by the signal from the mock (promoterless)–Myb vector (set to “1” in the bar graph). Fold changes and error bars are respective means and SDs calculated from triplicate wells. (C) Gata2 promoter activation by Twist1. Shown are analyses comparable to those in panel B.