Thus, ARID1A deficiency may generate the microsatellite instability genomic signature MSH2 by interacting with perturbations in M. Finally, in homozygous mice, cancers arising from ARID1A-deficient ovarian cancer cell lines exhibited high mutation loads, elevated PD-L1 expression, and increased numbers of lymphocytes in tumor infiltration. The gene discussed is CD274; the disease is ovarian cancer.