On the 27th of May, 2021, I defended my PhD at KU Leuven. The title of my thesis is 'The role of bistability and time delay in the coordination of the cell cycle'. Due to corona regulations only a limited number of people could attend, but fortunately we were able to have a drink outside afterwards. Thanks to everyone that was there, and especially to Lendert, my promotor, and the jury: Enrico Carlon, Karel Talavera Pérez, Edda Klipp and Jordi Garcia-Ojalvo.