Anti phospho s6

The human gastric cancer cell lines AGS, MKN1, and GT5 were purchased from American Type Culture Collection and previously described [19 (link)–21 (link)]. Patient-derived cells GA0518 were each isolated from ascites or PDX tumors from a patient with metastatic GAC [22 , 23 (link)]. All cell lines have been profiled and authenticated, in the Cell Line Core Facility at The University of Texas MD Anderson Cancer Center, every 6 months. The cell lines were cultured in the Roswell Park Memorial Institute Medium 1640 or Dulbecco modified Eagle medium supplied with 10% heat-inactive fetal bovine serum. The cells were maintained at 37 °C in a humidified incubator containing 5% CO₂. ARID1A knockdown cell lines (AGS ARID1A knock-down [KD] #1, AGS ARID1A KD #2, MKN1 ARID1A KD #1, and MKN1 ARID1A KD #2) were generated as previously described (Wang LL et al JCI 2020) and kindly provided by Dr. Guang Peng at MD Anderson Cancer Center. Chemotherapy agent 5-FU and mTOR inhibitor RAD001 were purchased from Sigma-Aldrich and Selleckchem, respectively. Antibodies used in this study were anti-ARID1A (HPA005456, Sigma-Aldrich) and anti–phospho-S6 (Cell Signaling Technology). Anti-SOX9 was purchased from Chemicon (EMD Millipore).