Figure 4 compares pathways which were activated or inhibited in host dendritic cells after infection with MDV. Several pathways were seen to be more downregulated in line 61 compared with line 72. These included GP6 signalling, tumour microenvironment, ERBB signalling, HIF1A signalling, HR2 signalling and phagocytosis. These are all processes associated with the immune system and/or tumour progression, and were more highly activated in the susceptible line 72 birds after challenge with MDV. The gene discussed is HIF1A; the disease is infection.