PDOswere generated from parent tumors of endometrioid carcinoma (EMCA), uterine papillaryserous carcinoma (UPSC), and carcinosarcoma (CS) EC subtypes (Supplementary Table S1).ARK1, ARK2, and all four PDO lines underwent limited whole exome sequencing analysis todetermine TP53, RB1, and other relevant gene mutationstatus (Supplementary Fig. S1A and S1B; Table 1).Publicly available data was utilized to obtain TP53 andRB1 mutation status for the other cell lines (Table 1; ref. 39). The gene discussed is RB1; the disease is Cowden syndrome 1.