NFKB1 and infection: Analogous to the case in mammals, elevations in ROS levels in Drosophila PSC cells caused by pathogen infection can activate NFκB/Toll signaling in hematopoietic progenitors and promote the differentiation of plasmatocytes and lamellocytes (see section “Role of the PSC in the Cellular Immune Response to Parasitic Wasp Infection”).