We first curated tumor-derived cell lines bearing intact expression of full-length ARID1A and ARID1B, those with loss of expression of ARID1A, and those characterized by dual-loss of ARID1A and ARID1B, isolated nuclear material and performed immunoblot analyses for mSWI/SNF family subunits (Fig. 1B–C, Extended Data Fig. 1F, Supplementary Table 2). Here, ARID1B is linked to neoplasm.