I am working on a model of aggregation behavior modeled with the Keller-Segel PDE system. I recently gave a talk on this and was asked what other examples there were of the Keller-Segel system. Since this is an obvious question, I was embarrassed to have no example other than my model and the aggregation of cellular slime molds (the application for which the Keller-Segel model was originally developed). So I did some googling and came up with bupkis. There are hundreds of papers about the system by mathematicians, but I failed to find any other biological examples.
What about it? Is the Keller-Segel model mostly just a mathematical curiosity, or is it a model with many real applications to biology?