In a multidisciplinary study newly published in the Journal of Cell Biology, the Barral group (D-BIOL/IBC) together with the Steinmetz group (PSI) and the Stelling group (D-BSSE), sheds light on how the motor domain of the kinesin protein Kip2 collaborates with the microtubule plus-end-binding protein Bik1, to moonlight as a microtubule polymerase.