Our group is interested in the regulation of fundamental cell biological and biochemical processes. The budding yeast Saccharomyces cerevisiae is an ideal system to study these processes due to the ease of manipulations and the high degree of conservation from yeast to man. We are particularly interested in p21-activated kinases (PAKs). These key signalling molecules have a surprisingly wide range of functions. In budding yeast, three different PAKs can be found: Ste20, Cla4 and Skm1. We are interested in the identification and characterisation of novel functions of PAKs, in particular of Ste20. We have previously shown that Ste20 regulates mitotic exit, sterol biosynthesis and uptake, and V-ATPase activity. At the moment we further investigate the role of Ste20 and Cla4 in metabolism and gene expression.