Cyclic GMP (cGMP) is a major mediator of relaxation in the vascular system. cGMP is produced by the enzyme soluble Guanylyl Cyclase (sGC) in response to nitric oxide (NO) released from neighbouring endothelial cells. cGMP activates Protein Kinase G (PKG), which in turn mediates vascular relaxation through phosophorylation of various targets. One of the major substrates of PKG is the VAsodilator-Stimulated Phosphoprotein (VASP). The role of VASP in vascular smooth muscle relaxation is currently unknown. However, recent studies show that VASP-deficient brown adipocytes have an increased activity of the small GTPase Rac1 and elevated levels of sGC [1]. These data suggest a regulatory role for VASP in cGMP-mediated processes.