The function of ENSG00000153404 (PLEKHG4B, pleckstrin homology and RhoGEF domain containing G4B) is as follows. Guanine nucleotide exchange factor (GEF) which specifically activates small GTPase CDC42 by exchanging bound GDP for free GTP. Plays a role in actin cytoskeletal remodeling in the late stage of cell-cell junction formation by regulating the contractility of actin filaments, which prompts the conversion from 'open' to 'closed' junctions. .