Fig 1: Smurf1 promotes receptor Smad degradation during chick gastrulation.(A) Gastrulating embryos were electroporated with H2B-RFP or V5-Smurf1; then, whole-embryo lysates were prepared at HH7. Ten µg total lysate was loaded per lane, and the resulting blots were processed for the indicated targets, with ribosomal S6 as a loading control. (B) Quantitation of protein expression normalized to ribosomal S6 levels showing means ± SEMs. Underlying data can be found in S1 Data. P values from two-tailed Student t test. BMPR1A, bone morphogenetic protein receptor type 1A; BMPR1B, bone morphogenetic receptor type 1B; H2B, histone 2B; NS, not significant; pSmad1/5/8, phospho-Smads 1/5/8; RFP, red fluorescent protein; Smurf1, Smad ubiquitin regulatory factor 1.