PTGS1 and infection: However, pharmacological inhibition of PG production, that is, inhibition of Ptgs1 and 2 (Fig. 8b) or specifically Ptgs2 (Supplementary Fig. 12B), fully reversed the higher infection resistance of larvae forced to express Gbp4 but, unexpectedly, the resistance of larvae forced to express Asc was unaffected (Fig. 8c).