This mutant form is characterised by increased switching from the inactive, GDP-bound to the active, GTP-bound state, which enhances the interaction of Rac1 with its downstream effectors.138 The RAC1 P29S mutant promotes the migration of melanocytes139 and invasion of mouse embryonic fibroblasts in vitro.140 Although melanoma cells (104T cell line) with the RAC1 P29S mutation form lamellipodia more actively, this mutant negatively affects the formation of invadopodia and invadopodia-dependent matrix degradation in vitro. The gene discussed is RAC1; the disease is melanoma.