Sym10

To perform the co‐immunoprecipitation experiment, we seeded A549 and ASTC‐a‐1 cells in 15 cm culture dishes and lysed the cells using lysis buffer (20 mM Tris pH 7.4, 150 mM NaCl, 2 mM EDTA, 2 mM EGTA, 1 mM sodium orthovanadate, 50 mM sodium fluoride, 1% Triton X‐100, 0.1% SDS and 100 mM phenylmethylsulfonyl fluoride). Afterward, we centrifuged the lysates at maximum speed for 10 min at 4°C, and the cleared cell extracts were pre‐cleared with protein A and protein G beads (Santa Cruz Biotechnology, cat# sc‐2001 and cat# sc‐2002) at 4°C for 1 h. We then added 5°μg of primary antibodies, including PRMT5 (Santa Cruz Biotechnology, cat# sc‐376937), KLF5 (Cell Signaling Technology, cat# 51586), SYM10 (Millipore& Sigma, cat# 07‐412), HA (BioLegend, cat# 901502) or isotype IgG to the cleared cell extracts and incubated them overnight at 4°C. Next, we incubated the cell extracts with protein A or protein G beads at 4°C for 3 h, followed by three washes with wash buffer (100 mM NaCl, 50 mM Tris pH 7.5, 0.1% NP‐40, 3% glycerol and 100 mM phenylmethylsulfonyl fluoride). Finally, we eluted the beads‐bound proteins by adding 1× Laemmli sample buffer and heating at 95°C for 10 min. We analysed the protein–protein interactions using western blotting.