FIGURE 9.

Schematic diagram of cross-regulation between Klf1, Klf3 and Klf8. Klf1 activates expression of the Klf3 and Klf8 gene promoters. The Klf8 promoters can also be repressed by Klf3. In tissues where both Klf1 and Klf3 are present, such as fetal liver, the proteins compete for binding, and this restricts Klf8 to low levels of expression. In the absence of Klf3, for example in the Klf3 null fetal liver, Klf1 gains access to the Klf8 promoters, resulting in de-repression of the gene and increased Klf8 protein.