Fig. 2. Activation of endogenous Xral by Ras 12V37G. (A) Protein from embryos injected with 2x 500 pg of Ras 12V35S, Ras 12V37G or Ras 12V37G in combination with 3 ng of XralB S28N, were extracted (128-256 cell stage), the Ral-GTP was immunoprecipitated with RalBD-conjugated glutathion-sepharose, and total Ral protein in whole-embryo lysates were detected subsequent to SDS-PAGE by immunoblotting with specific antibodies, as described in the Materials and Methods. The signal from each Ral-GTP band from experiments was quantified by densitometry and analysed by Image-Quant. The values express the ratio of the immunoprecipitated Ral-GTP signal/total Ral protein signal. (B) Animals caps explanted from embryos injected either with Ras 17N or Rap1A (2x 500 pg) mRNAs at 2-cell stage was analysed for the activated form of Xral as described in Fig. 1.