FOS and infection: In the JNK pathway [58], which controls genes that participate in wound healing and cellular immune processes including hemocyte proliferation and differentiation [59], we found that both axenic and symbiotic Heterorhabditis as well as Photorhabdus infection upregulated Kayak (the Drosophila Fos homolog), while infection with symbiotic nematodes and the bacteria alone upregulated Basket (the Drosophila JNK homolog) at 12 and 30 h post-infection, respectively.