Transcription factor that binds to the promoter of target genes (PubMed:26305787, PubMed:16168406, PubMed:26341465). Regulates genes involved in serotonin synthesis and release in serotonergic ADF neurons (PubMed:26305787, PubMed:16168406). Involved in specification of neuron cell fate, olfactory receptor expression, locomotion, and foraging behavior (PubMed:10421632, PubMed:26305787). Required in AWB olfactory neurons to repress AWC cell fate and promote the AWB cell fate during early development (PubMed:10421632). Cooperates with additional factors to direct the differentiation of the olfactory neurons, functioning with the transcription factor sox-2 to suppress AWC terminal differentiation and promote AWB neuron differentiation (PubMed:26341465). Involved in regulating terminal specification and maintenance of the SMB sensory/inter/motor neurons (PubMed:26305787). Plays a role in regulation of RID motor neuron differentiation, but is dispensable for motor axon outgrowth in the dorsal nerve cord (PubMed:14568548). May regulate its own expression (PubMed:10421632, PubMed:26305787). Interacts with transcription factor sox-2. Expressed in the AWB sensory neurons and in one RME motor neuron (RMEV), two RMD motor neurons (RMDL and RMDR), the RID, RIV, SAA and SIA interneurons and the SMB sensory/inter/motor neurons. Expressed in larvae and adults in neurons in the anterior ganglia (PubMed:10421632). Expressed in the precursor of serotonergic ADF neurons (PubMed:16168406). Expressed in the SMB sensory/inter/motor neurons at larval stage L1 (PubMed:26305787). It has been reported that lim-4 is expressed in the SIA interneurons (PubMed:10421632). However, a subsequent report suggests that this was a mis-identification, instead indicating that the correct cell type is the SMB sensory/inter/motor neuron (PubMed:26305787).