Probably an atypical receptor-regulated SMAD (R-SMAD) that is an intracellular signal transducer and transcriptional modulator activated by TGF-beta-like daf-7 signaling (PubMed:10625546). Plays a role in TGF-beta-like daf-7 signaling in regulating entry into a developmentally arrested larval state known as dauer, in response to harsh environmental conditions; partially redundant with R-SMAD daf-8 (PubMed:10625546, PubMed:20081192). Interacts with R-SMAD daf-8 and co-SMAD daf-3 (PubMed:20081192). Interacts with daf-3 in a daf-8 dependent manner (PubMed:20081192). Widely expressed in all stages from the embryo to the adult in a complex and dynamic pattern (PubMed:10625546). In L1 and L2 stage larvae, expressed in intestinal cells, lateral hypodermal cells, the anal sphincter muscle, phasmid sheath cells, neurons in the lateral ganglia, and the excretory duct cell (PubMed:10625546).