Fig. 5. Loss of the cryptic proteolytic cleavage site in Xnr2 has no impact on activity. (A) RT-PCR analysis of the xnr2 upstream cleavage mutant construct (UCM-xnr2). Embryos were injected in the animal pole at the one-cell stage with 1 pg or 10 pg of xnr2 or UCM-xnr2 mRNA. Both molecules induce the mesoderm markers xbra and vegT at equivalent doses (lanes 1 and 4). (B-E) Analysis of UCM-xnr2 in whole embryos. Embryos were injected at the one-cell stage with 0.1 pg or 1 pg of xnr2 or UCM-xnr2 mRNA and allowed to develop to stage 20.