Skip to main content
. 2000 Jan 15;14(2):177–186.

Figure 1.

Figure 1

Rhomboid- (Rho) and Star-dependent mSpi activation of DER in Xenopus animal caps. (A) Models for Rhomboid and Star action. (B) RPA showing that Rhomboid and Star each weakly promote mSpi activation of DER, however, together they are synergistic (lanes 2–5). sSpi activates DER in the absence of Rhomboid and Star (lane 1). Argos represses sSpi activation of DER (lane 7). (C) Induction of XBra expression by DER is reduced in the presence of the dominant-negative FGF receptor, XFD (compare lane 1 with 3, and lane 2 with 5). In a positive control for the potency of XFD, lanes 6 and 7 show that XFD abolishes induction of XBra by activin. (D) Sandwich assay experimental design. (E) RPA of animal cap sandwiches showing that Rhomboid and Star must be coexpressed with the ligand, and not the receptor, for activation to occur (lanes 2–4). When Rhomboid and Star are present in both the signaling and receiving cells, the level of DER activation is attenuated (lanes 5–7).