Achim came to the lab after his graduate work in Frauke Melchior’s lab at the ZMBH in Heidelberg, Germany. There, Achim had found an intriguing role for ubiquitin in controlling the actin cytoskeleton during cell division. In our lab, Achim developed both genetic and proteomic screens to discover a unique role of multi-monoubiquitylation to control new protein synthesis and neural crest specification (Werner et al., Nature 2015). While inhibition of the key ubiquitylation event found by Achim causes Treacher Collins Syndrome, mutations that activate the critical E3 ligase, CUL3KBTBD8, are drivers of melanoma, a cancer of neural crest origin. As expected for a core developmental circuit, ubiquitin-dependent control of neural crest specification is very robust – in part, because the E3 ligase can recognize up to 12 degron sequences in the same substrate (Werner, Baur, et al., eLife 2018).