EWSR1 and hidradenoma: Although we have shown that EWS-Oct-4B regulates the expression of fgf-4 and nanog, which are known potent mitogens (Figure 7), it remains to be seen whether the activation of fgf-4 or nanog through EWS-Oct-4B is sufficient to produce the neoplastic phenotype found in the two types of epithelial tumours, hidradenoma of the skin and mucoepidermoid carcinoma of salivary glands.