The direct conversion of adult somatic cells to oligodendroglia through Oct4 expression relies on the composition of the culture medium and, in particular, on the spontaneous silencing of the Oct4 transgene after a few weeks; otherwise, as Oct4 can promote the generation of neural stem cells from human fibroblasts (Mitchell et al., 2014) and iPSCs from neural stem cells (Kim et al., 2009), the final product would be iPSCs, which could lead to the generation of teratomas when these cells are transplanted. The gene discussed is POU5F1; the disease is teratoma.