Fig. 1. Ngn3 is degraded by ubiquitin-mediated proteolysis in interphase and mitosis.

Degradation assays were performed in interphase (A) and mitotic (B) Xenopus egg extract using ³⁵S-IVT Ngn3 in either the presence or absence of 100 µM Mg132 proteasome inhibitor. Samples were run on SDS-PAGE gels, analysed by autoradiography (A,B) and quantified by phosphorimaging (C). Degradation half-lives were calculated using first-order rate kinetics (D). In C, the solid line shows degradation in interphase extracts, and the dotted line shows degradation in mitotic extracts.