RAC1 and melanoma: The P29S mutation was identified as one of the major somatic mutations in melanoma (Hodis et al., 2012; Krauthammer et al., 2012), and was shown to increase the affinity of Rac1 for the effectors PAK1 (p21 protein activated kinase 1) and MLK3 (mixed-lineage kinase 3) (Hodis et al., 2012; Krauthammer et al., 2012).