USP4 and ovarian neoplasm: In the present study, we observed that PIK3R3 expression increased in ovarian tumors with somatically mutated USP4, SPTBN1, and SORBS2 but decreased in those with somatically mutated TBC1D2, implying that USP4, SPTBN1, TBC1D2, and SORBS2 mutations in ovarian cancer are closely related to PIK3R3 expression.