Guanine nucleotide-exchange factor (GEF) that activates CDC42 by exchanging bound GDP for free GTP (PubMed:37342957). Required for marginal zone (MZ) B-cell development, is associated with early bone marrow B-cell development, MZ B-cell formation, MZ B-cell number and marginal metallophilic macrophages morphology (By similarity). Facilitates filopodia formation through the activation of CDC42 (PubMed:37342957). {ECO:0000250|UniProtKB:A2AF47, ECO:0000269|PubMed:37342957}. This is the function of ENSG00000147251 (DOCK11, dedicator of cytokinesis 11).