Bone morphogenetic proteins (BMPs) play important roles in the course of biological processes such as cell growth, and differentiation. In embryonic development in Xenopus laevis, BMPs are involved in mesoderm induction during blastula stages, and mesodermal patterning and neural induction during gastrulation. The dorsal-ventral patterning of the embryo is regulated by the level of BMP signaling. There are three inputs regulating the intensity of BMP signal; the level of BMP ligand, which is highest at ventral region, the level of BMP antagonists, which are secreted from the organizer, and down-regulation of Smads within the cell by ubiquitination. Smurf1 is a SMAD ubiquitin ligase that targets the BMP pathway, altering embryonic development in Xenopus. Recent studies have proven Smurf1 to interact with receptor-regulated SMADs of BMP pathway resulting in their ubiquitination. Ubiquitinated Smad proteins are then directed for proteolysis. A yeast two-hybrid screen that was performed, prior to this experiment, which showed the interaction of Smurf1 with the SMAD signaling pathway also yielded another protein; Ubiquilin1. Ubiquilin1 has two ubiquitin-related domains, UBA and UBL. Although there are conflicting reports in the literature, ubiquilin-1 most probably functions as an adaptor between tagged proteins and proteosome machinery. We hypothesized that Ubiquilin1 might be involved in the ubiquitination and proteolysis of Smad1 either by helping Smurf1 to send Smad proteins into proteosome or it may be involved in a novel mechanism designed to protect Smad proteins from Smurf-1 regulated ubiquitination by blocking Smurf-1 binding via masking the binding interface. This study was designed in order to determine which role Ubiquilin1 would take in the embryonic development of Xenopus laevis. Two distinct tests were carried out to obtain conclusions from separate perspectives. The expression of Ubiquilin1 was tested by in situ hybridization, while the impact of this gene was tested by RNA injection. For in situ hybridization, after an in vitro fertilization, albino and pigmented embryos were collected at different stages of development. These embryos were fixed in MEMFA fixative and stored at -20°C in 100% ethanol. After setting the synthesis reaction for the Sense and Anti-Sense probes, embryos were prepared for in situ hybridization. They were rehydrated for staining by decreasing the concentration of ethanol. A Proteinase K treatment and triethanolamine washes followed the procedure. Probes were hybridized overnight. Dig-labeled probes were detected with alkaline phosphotase-conjugated anti-digoxygenin antibody. The color reaction was carried out with BM Purple (Roche) containing levamisole. In situ hybridization has not yet yielded sufficient staining results; however, tests are still being carried out. On the other hand, the RNA injections, which were made both on the dorsal and ventral sides in varying concentrations, have not adequately satisfied the experiment's anticipation yet. Meanwhile, these injections are being varied, improved and repeated. Again, there are two pathways, towards which the study can shed light. If findings show that Ubiquilin1 promotes dorsal development such as head, neural tissue, and mesoderm, it would be concluded that it plays the same role as Smurf1 in ubiquitination of Smad1. However, if results produce less neural development and loss of head structures, Ubiquilin1 would then be associated to blocking ubiquitination of Smad1 by Smurf1. This study was supported by the Simons Foundation.