ATF2 and infection: We also tested if known p38 phosphorylation targets were required in ECs to promote ISC response to infection by assessing whether ISC proliferation was affected in P.e.-infected flies mutant for the transcriptional regulator Atf2 (Atf2PB)41 or in flies depleted for Atf2 in ECs, or mutant for MAPK-activated protein kinase 2 (MAPKAP-K2 or MK2)40.