Antibodies were optimised on human tissue, HCT116 ARID1A isogenic (mutant and wild‐type) cell lines, ES2 (ARID1A wild‐type), TOV21G (ARID1A mutant) ovarian clear cell carcinoma cell lines, and in HCT116 ARID1A isogenic xenograft models (Figure 1B‐D). The gene discussed is ARID1A; the disease is ovarian clear cell cancer.