Involved in cytoskeletal rearrangements required for lymphocyte migration in response of chemokines. Activates RAC1 and RAC2, but not CDC42, by functioning as a guanine nucleotide exchange factor (GEF), which exchanges bound GDP for free GTP. May also participate in IL2 transcriptional activation via the activation of RAC2. Homodimer (Probable). Interacts with RAC1 and RAC2. Interacts with CRKL and VAV. Interacts with CD3Z. Colocalizes with F-actin. Specifically expressed in hematopoietic cells. Highly expressed in peripheral blood leukocytes, and expressed at intermediate level in thymus and spleen. Expressed at very low level in the small intestine and colon. The DOCKER domain may mediate the GEF activity. The disease is caused by variants affecting the gene represented in this entry. Splicing donor and acceptor sites between exon 6 and exon 7 are not canonical. Belongs to the DOCK family. Extended N-terminus.