POU5F1 and hidradenoma: Because the properties of EWS-Oct-4B are very similar to those of EWS-Oct-4, it would be interesting to investigate whether abnormal expression of EWS-Oct-4B in two types of epithelial tumours, hidradenoma of the skin and mucoepidermoid carcinoma of salivary glands, also contributes to the induction of the incomplete embryonic transition.