RAC1 and focal segmental glomerulosclerosis: Additionally, ARHGDIA mutations [103] and ARHGEF17 mutations [104] (the genes encoding GDI and GEF, respectively) were also found in FSGS, both of which were closely relevant to the pathogenesis of FSGS (Figure 1), confirming that increased Rac1 activity was essential for podocyte injury and proteinuria.