An EcR homolog from the filarial parasite, Dirofilaria immitis requires a ligand-activated partner for transactivation.

DiEcR is a Dirofilaria immitis nuclear receptor that shares many biochemical properties with insect EcRs, including ligand-dependent activation of transcription. However, DiEcR differs from insect EcRs in that it requires a ligand-activated rxr partner for its transcriptional activating activity.