ATF4 and head and neck squamous cell carcinoma: ChIP-qPCR assays clearly showed ATF4 bound to the FGF19 promoter in HN12 cells (Fig. 2h) and increased amount of ATF4 at the FGF19 promoter binding site in the presence of 5 mM MT (Fig. 2i), indicating that MT-induced ER stress promotes ATF4 upregulation, which in turn transcriptionally activates FGF19 in HNSCC cells.