Another posttranslational modification that may impact palmitoylation dynamics is nitrosylation. Nitric oxide (NO) is produced from l-arginine by NO synthase enzymes (NOS) and can directly modify cysteines by S-nitrosylation (Stamler et al., 1992) ; this modification might therefore regulate palmitoylation dynamics by direct competition. The NO donor SIN-1 inhibited the basal level and the isoproterenol-stimulated increase in palmitate incorporation into 2 adrenergic receptor (Adam et al., 1999) . Palmitate incorporation into H-Ras, caveolin, SNAP25, and certain viral proteins has also been reported to be modified by NO donors (Hess et al., 1993; Baker et al., 2000; Akerström et al., 2009) . Indeed, the NO donor S-nitrosocysteine accelerated removal of radiolabeled palmitate from H-Ras in pulsechase experiments (Baker et al., 2000) , raising the intriguing possibility that NO may directly displace palmitate from modified proteins (Fig. 3 C) .