Fig. 5. Inefficient activation of Smad proteins in ß4GalT5MO embryos. (A,B) Epiboly stage embryos were lyzed and assayed for (A) total or (B) activated Smad proteins by western immunoblotting, which was scanned and quantified. Levels of R-Smads (assayed using an anti-Smad5 antibody) and phospho-R-Smads (assayed using anti-phospho Smads1/5/8) were normalized to total protein loads. Expression is presented relative to control levels. No difference in the levels of total R-Smads was detectable between control-injected and ß4GalT5MO-injected embryos, although activation of the Smad1/5/8 complex was reduced by 73% in ß4GalT5MO embryos. Similar results were obtained in three separate experiments using both translation-blocking and splice-blocking morpholino oligonucleotides. Error bars indicate s.e.m.