TLR4 and infection: Infection of D. melanogaster with the B. bassiana or M. anisopliae (fungi) resulted in elevated gene expression for the antifungal peptide drosomycin and metchnikowin; however, no increase was observed for the antibacterial peptides diptericin or cecropin A. Various fungi can also stimulate the antimicrobial peptide attacin A through the Imd and Toll pathways, thus activating the transcription factors Relish and/or Dif, as observed in the Dif and Relish mutants of D. melanogaster.