TROP2 protein expression is strong in parental choriocarcinoma cell lines (CC, JEG-3, BeWo) and their cisplatin-resistant subclones (e.g., JEG-3-R), while embryonal carcinoma cell lines (EC, NCCIT, 2102EP), the EC-YST intermediate line (1411H), and their resistant derivatives lack detectable TROP2 expression (Fig. 2A). The gene discussed is TACSTD2; the disease is embryonal carcinoma.