Fig. 6. Analysis of Epha3 and Sgk expression in the HoxD^Del1-10 gain-of-function mutant. (A) Anterior gain of Hoxd13 expression (arrow) in an E11.5 HoxD^Del1-10 right forelimb. (B) Epha3 expression is completely abolished in the region where Hoxd13 expression is gained (arrow). This observation contrasts with the increased Epha3 expression seen in HoxD^Del1-13 mutant limbs (Fig. 5B), further supporting Epha3 as a candidate gene for Hoxd repression. Complete Epha3 repression was observed in 11 out of 12 HoxD^Del1-10 forelimbs stained. (C) By contrast, Sgk expression is gained in the region of presumptive digit 1 (arrow) in the HoxD^Del1-10 forelimb. This weakly stained domain was visible in eight out of eight mutant E11.5 forelimbs. Accordingly, Sgk expression was lost in the E11.5 HoxD^Del1-13 mutant (see Fig. 3A), indicating that Sgk is upregulated by Hoxd gene expression.