TACSTD2 and yolk sac tumor: TROP2 mRNA and protein expression levels were analyzed in 31 post-chemotherapy viable MET(-R) specimens, including embryonal carcinoma (EC), choriocarcinoma (CC), yolk sac tumor (YST), and teratoma (TER), using quantitative reverse transcription polymerase chain reaction and immunohistochemistry with H-score evaluation.