Transcription factor. First expressed within the dorsolateral ectoderm, except for the organizer territory. During gastrulation, expressed in 2 ectodermal stripes adjacent to the dorsal midline. With the onset of neurulation, expression shifts first to the neural plate before settling on the bottom of the neural tube, on top of the notochord. Expression is then absent until stage 35, at which stage a pair of cells in the fourth rhombomere in the dorsolateral outer area of the rhombencephalon show expression. This is followed shortly afterwards by expression in a pair of cells in rhombomere 6 at the ventricular side of the rhombencephalon. Expression begins after the mid-blastula transition, peaks during gastrulation and is completely extinguished at the end of neurulation, before reappearing in swimming tadpoles.