Probable secreted lin-12/Notch ligand or co-ligand involved in the mediation of Notch signaling (PubMed:18700817, PubMed:21549604). Involved in the lin-12/Notch pathway signaling of cell fate in vulval precursor cells (VPCs), acting redundantly with dsl-1 and lag-2 (PubMed:18700817). Required for normal octanol avoidance response, acting via both lin-12/Notch and glp-1/Notch signaling pathways in neurons, in concert with lag-2 (PubMed:21549604). Involved in regulation of sleep-like quiescence during the larval to adult transition, acting via Notch receptor activation and in parallel with EGF signaling (PubMed:21549604). May interact with lin-12/Notch receptor. Concentrated on the apical surface of vulval precursor cells. Expressed in coelomocytes (at protein level). Expressed in VPCs and hypodermal cells during larval development (PubMed:18700817). Expressed in VPCs of L3 stage larvae prior to and during cell fate specification and in the seam cells of L1 stage larvae and adult animals (at protein level) (PubMed:18700817). Expressed in developing uterus of L4 stage larvae and in the spermatheca (at protein level) (PubMed:18700817). RNAi-mediated knockdown causes moderately abnormal vulval development (PubMed:18700817). RNAi-mediated knockdown causes defects in octanol response (PubMed:21549604).