... combination of expression plasmids of HA–Rac1L61, HA–Rac1bWT, HA–Rac1bL61 and 6His–myc–Ub as indicated. Proteasomal degradation of Rac1L61 and Rac1b (right panel). Proteasomal degra-dation was assessed ... moreresistant to proteasomal degradation than Rac1L61. Mutational analysis ofall lysine residues in Rac1 revealed that the major target site for Rac1ubiquitination is Lys147, a solvent-accessible ... (Fig. 3A, right panel),indicating that the stimulation of Rac1-dependentpathways may, in some way, activate the Rac1 ubiqui-tination machinery.As Rac1b has been shown to display reduced capac-ity...