Functions as a transcriptional regulator. Functions in the differentiation and the maintenance of the central serotonergic neurons. May play a role in cell growth (By similarity). Expressed by serotonergic neurons in anterior and posterior raphe. Expressed in post-mitotic raphe serotonergic neurons. First detected at the 20 somites stage. Belongs to the ETS family. It is uncertain whether Met-1 or Met-14 is the initiator.