<i>dys</i> molecular regulation and model for tarsal joint development.

<p>(A) Schematic representation of a tarsal joint of a <i>dys640</i> wild type (left) and <i>dys640^Su(H)-1+2</i> where the two Su(H) binding sites are mutated (right). See text for description. (B) Model for tarsal joint formation. Blue and brown arrowheads mark proximal and distal joints, respectively. In a tarsal joint, Notch ligands Dl and Ser (blue) activate the Notch pathway in the distal adjacent cells. Notch, in turn, activates <i>dys</i> expression, which regulates the high levels of P-Mad observed in the joint. Dys also controls the expression of the pro-apoptotic genes <i>rpr</i> and <i>hid</i> and the RhoGTPases modulators <i>RhoGef2</i> and <i>RhoGap71E</i>. The sharp boundary of Dpp signaling also regulates <i>rpr</i> expression via JNK pathway activation. The expression domains of <i>E(spl)mβ</i>, <i>dys</i>, <i>rpr</i>, <i>hid</i>, <i>RhoGef2</i> and <i>RhoGap71E</i> are indicated.