A 56-year-old woman has had weight loss accompanied by abdominal enlargement for the past 5 months. There is a family history of breast and ovarian carcinoma. On physical examination, there are no lesions of the cervix, and the uterus is normal in size, but there is a left adnexal mass. An abdominal ultrasound scan shows a 10-cm cystic mass in the left adnexal region, with scattered 1-cm peritoneal nodules, and ascites. Cytologic studies of peritoneal fluid show malignant cells. Which of the following mutated genes is most likely a factor in the development of this neoplasm?