Small GTPases and cell polarization

Here I connect some of the background already discussed to the concepts of GTPase activity and bistability in the context of cell polarization. I explain in detail how the ideas of bistability were used to reject some competing hypotheses for mutual interactions of Cdc42 and Rho (two GTPases implicated in cell motility and polarization), and how mathematical models were then gradually assembled based on the remaining hypotheses. I discuss both mutual inhibition and positive feedback as
possible mechanisms. I then introduce the evidence for Cdc42-Rho interactions based on a collaboration with William Bement. This is further explained in a lecture by Cory Simon, former UBC PhD student.