Over-representation analysis (ORA) for upregulated DEGs after 2 days of FGF8 treatment showed the most-enriched Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways, i.e. cancer-related pathways, PI3K–Akt signaling, MAPK signaling and TNF signaling, as well as the most-depleted KEGG pathways, i.e. metabolic pathways, herpes simplex virus 1 (HSV1) infection and olfactory transduction (Fig. 5B). The gene discussed is TNF; the disease is infection.