**2.4 Subfamily 4 and 6**

NR4A was the only subfamily 4 member identified in parasitic platyhelminths. Phylogenetic analysis suggested that it is orthologue of *Drosophila*, Mollusca, and human NR4A receptor [49]. The relative mRNA expression level of SmNR4A5 from *S. mansoni* was similar in egg, adult female, and adult male [71].

Concerning subfamily 6 of NRs, only one member of subfamily 6 (MlNR6) identified belongs to the free-living flatworm *Macrostomum lignano* [49].
