ARNT and infection: Thus, infection with E. coli in D. melanogaster that lacks Ird5 (the homologous of IKK, that activates the Relish protein by phosphorilation), produces a decrease in the synthesis of drosomycin and a reduction in the expression of HIF-1α and HIF-1β, genes homologs called sima and tango, respectively (20, 21).