POU5F1 and teratoma: However, the parental cells of JEG-3 did not show the expression of Oct4. Looijenga and Oosterhuis (2013) showed that some of the teratoma tumour cells (including choriocarcinoma cells) did not express Oct4. However, parental cells (untreated and treated) of BeWo exhibited immunofluorescence for Oct4. In the case of spheroids, Oct4 (together with other stem cell markers) expression is observed in both cell lines.