KLF4 and infection: GDF15 gene expression can be upregulated in different situations of cellular stress caused by e.g., inflammation, infection, neoplasia, ionizing irradiation as well as different drugs via various transcription factors such as p53, kruppel-like factor-4 (KLF4), early growth response protein 1 (EGR1), hypoxia-inducible factor-1α (HIF-1α), activating transcription factor 3 and 4 (ATF3, ATF4), and C/EBP homologous protein (CHOP) [18,26,29].