Bistability plays an important role in many biochemical processes and typically emerges from complex interaction patterns such as positive and double negative feedback loops. Jolan and Jan explicitly incorporated a functional expression describing an S-shaped input-output curve in the model equations, without the need for considering the underlying biochemical events. Using such approach, we then constructed a cell cycle model consisting of multiple bistable switches, accounting for a number of known properties of the cell cycle. Nice work Jolan and Jan! Read more here in our PLoS Comp. Biol. paper.