RT-qPCR was performed as described previously (13 (link)). Briefly, total RNA was extracted from GBC-SD cells using TRIzol® reagent (cat. no. 15596018; Invitrogen; Thermo Fisher Scientific, Inc.) according to the manufacturer's protocol. A total of 1 µg total RNA was used as the template for cDNA synthesis using a reverse transcription kit (cat. no. K1691; Thermo Fisher Scientific, Inc.). Equal quantities of cDNA were used for PCR analysis. The sequences of the primers were: c-FLIP forward, 5′-CGCTCAACAAGAACCAGTG-3′and reverse, 5′-AGGGAAGTGAAGGTGTCTC-3′; and β-actin forward, 5′-AGTGTGACGTCGACATCCGC-3′ and reverse, 5′-GACTCGTCGTACTCCTGCTT-3′. PCR primers were purchased from Sangon Biotech Co., Ltd.