Other genes in this group include CG31508, encoding a small protein with no characterized function, that had previously been identified to be strongly induced in the gut upon infection in a Rel-dependent manner [33], a fibrinogen-related protein gene (CG5550), a gene encoding a potential constituent of the gut peritrophic matrix (CG7248) and a peptidoglycan recognition protein gene (PGRP-SC1b), which acts as a negative regulator of immunity-regulating signal transduction pathways [29]. This evidence concerns the gene REL and infection.