Dynamic cellular processes such as the assembly and function of the mitotic spindle, and the transport of macromolecules between the nucleus and cytoplasm, are the product of dynamic interactions between protein molecules. These interactions may involve regions of proteins that are intrinsically disordered, and which adopt a regular structure only transiently whilst in complex with their partner. We investigate these fascinating systems using a combination of structural, computational and cell biology approaches. One example is the MYC family of transcription factors whose interactions are regulated by Aurora-A (B├╝chel, Cell Reports 2018). The crystal structure of the Aurora-A/N-MYC complex explained why this interaction stabilizes N-MYC and how this can be reversed by certain inhibitors of Aurora-A (Richards, PNAS 2016).