We study cell signalling in mammals by an approach that we call "in vivo biochemistry". To this end, we use state-of-the-art transgenic mouse technology and try to "watch" biochemical processes in real time in living cells, tissues and mice. Specifically, we are interested in the role of the signalling molecule cGMP in health and disease, with a current focus on cell growth and plasticity in the mammalian cardiovascular and nervous system. The projects involve analyses at the whole organism, cellular and molecular level.