Plays a critical role as a guanine nucleotide exchange factor (GEF) for CDC42 in several intracellular processes associated with the actin and microtubule cytoskeleton (By similarity) (PubMed:26895965). Plays a central role in renal ciliogenesis and kidney development (PubMed:26895965). Expressed from 1 dpf in the brain and pronephric tubules. At 3 dpf, expression expanded to the eyes and neuromasts, where mechanosensory hair cells exist, along the lateral line. The morphants contained multiple phenotypic defects, beginning with a downward-curled tail at 2 dpf. Additional ciliary defects after 3 dpf included small eyes, pericardial edema and hydrocephalus. These defects became more severe, leading to abdominal fluid accumulation, as well as abnormal pronephric kidneys at 5 dpf.