Human ESCC cell lines (KYSE450, KYSE510) and the human embryonic kidney cell line (HEK293T) were purchased from American Type Culture Collection (ATCC; Manassas, VA). Each vial of frozen cells was thawed and maintained in culture for a maximum of 8 weeks. All cells were cytogenetically tested and authenticated before freezing. All cell culture conditions were performed following ATCC’s instructions.