BMAL1 and cancer: Apoptosis is a key process in the anti-cancer treatment of ESCC.24 Multiple studies have validated the pro-apoptotic roles of ARNTL in human tumor cells, including glioblastoma, melanoma, tongue squamous cell carcinoma, and pancreatic cancer.12,25–27 Consistent with these reports, our study found decreased ARNTL expression in ESCC and confirmed that its upregulation could promote ESCC cell apoptosis and inhibit tumorigenesis in vivo.