To identify the potential interaction protein that interacts with BCAT1 by IP-MS, we established the stable cell line with vector and BCAT1 in AGS. Then ten million cells were collected lysed in ice-cold 0.1% NP-40 buffer (50 mM Na2HPO4, pH 7.5, 150 mM NaCl) with protease inhibitors cocktail (Sigma, p8340). The supernatants were collected by centrifugation and incubated with 10 µL Anti Flag‐beads (Sigma, A2220at 4°C for overnight. After incubation, beads were washed with lysis buffer for 3 times. Precipitates were resuspended in 1 × SDS loading buffer and separated by SDS-PAGE (polyacrylamide gel electrophoresis). Then cut off (about 1cm2) gel for trypsin hydrolysis and collected and dried the peptide for MS analysis (Thermo Fisher Q Exactive).