To confirm this differential growth effect of proteasome inhibition on ARID1A wild-type and mutant lines, we applied physiological concentrations of oprozomib, a second-generation proteasome inhibitor in trial for the treatment of hematological cancers (Sherman and Li, 2020), and measured the difference in growth rate. The gene discussed is ARID1A; the disease is hematopoietic and lymphoid cell neoplasm.