Fig. 4.

Expression driven by the Ndg enhancer is de-repressed in the heart by mutating any of the Fkh sites. (A-F″′) The posterior-most four cardial cells (the Tin-Lb-CCs and the Tin-CCs) are marked by Tin expression (red), and the Odd-PCs are marked by Zfh1 expression (blue) in abdominal segments A3 and A4. (A-A″′) The GFP reporter driven by the wild-type Ndg enhancer is expressed in only two cardial cells per hemisegment (green): the Tin-Lb-CCs (square bracket). (B-F″′) Mutations in one or more of the Fkh-binding sites result in the de-repression of reporter expression in additional CCs (arrows) and into the Odd-PCs (arrowheads). (G,H) Histograms showing the mean number of cells expressing the reporter and the significance of de-repression into CCs (G) and Odd-PCs (H) as a result of Fkh-binding site mutations.