GTPase-activating proteins (GAPs) accelerate the intrinsic rate of GTP hydrolysis of Ras-related proteins, resulting in downregulation of their active form. ARHGAP30 (Rho GTPase activating protein 30), also known as Rho-type GTPase-activating protein 30, is a 1,101 amino acid protein that contains one Rho-GAP domain and exists as four alternatively spliced isoforms. Conserved in chimpanzee, dog, cow, mouse and rat, ARHGAP30 is among the most neurite-enriched GAPs, which also includes ARHGAP21, FNBP2 and Bcr). One of four single-nucleotide polymorphisms (SNPs) at the USF-1 gene locus, rs2774279, which is located in the promoter area of the USF-1 gene, which is in turn located within its flanking gene ARHGAP30, is linked to low-density lipoprotein cholesterol levels, incident type 2 diabetes mellitus and increased cardiovascular risk.