Adapter protein which modulates signaling mediated by several receptor tyrosine kinases such as egl-15 and let-23 probably acting upstream of let-60/ras. Negatively regulates vulva induction probably downstream of let-23 (PubMed:1372395, PubMed:16547100). Involved in sex myoblast migration (PubMed:1372395, PubMed:9073451). Negatively regulates fluid homeostasis probably downstream of egl-15 (PubMed:1372395, PubMed:11689700). During the formation of neuromuscular junctions at the larval stage, negatively regulates membrane protrusion from body wall muscles probably downstream of egl-15 (PubMed:16495308). Involved in cytoskeleton dynamics and is recruited by mig-13 to the leading edge of Q neuroblasts and their descendants to signal downstream to activate the wsp-1 pathway and direct migration along the anteroposterior body axis during larval development (PubMed:27780040). Involved in let-23-mediated regulation of fertility independently of let-60/Ras (PubMed:16547100). Negatively regulates daf-2-mediated repression of dauer formation (PubMed:16547100). Plays a role in nicotinic acetylcholine receptor (nAChR)-mediated sensitivity to nicotine (PubMed:15990870). Regulates synaptic levels of nAchR subunit lev-1 in the nerve cord (PubMed:15990870). May play a role in oocyte development upstream of let-60/Ras and the MAP kinase pathway (PubMed:12169634). Interacts (probably via SH3 domain 2) with soc-1 (via C-terminus) (PubMed:16547100). Interacts with mig-2 (active GTP-bound form) and wsp-1 (PubMed:27780040). Interacts with mig-13; the interaction is direct (PubMed:27780040). Targeted to the leading edge of Q neuroblasts by mig-13. Expressed in body wall muscles, pharynx, intestine and hypodermis. RNAi-mediated knockdown or RNAi-mediated knockdown in body wall muscles causes ectopic membrane extensions from body wall muscles. Belongs to the GRB2/sem-5/DRK family.