SKOV3, an originally putative serous cell line, harbors mutations in TP53, PIK3CA, ARID1A, and gene amplification in ERBB2 and CCNE1 loci, which are often identified in high-grade ‘ovarian’ endometrioid tumor or in the ‘uterine’ serous tumor. The gene discussed is ARID1A; the disease is endometrioid tumor.