During development, many neurons display calcium-dependent migration, but the role of this messenger in regulating gene expression leading to this event has not yet been elucidated. Among the decoders of calcium signals is calcineurin, a Ca²⁺/CaM serine/threonine phosphatase that has been involved in both short term and long-term cellular changes. By using immortalised GnRH-secreting neurons, we now show that, in vitro, Ca²⁺-dependent gene expression, proceeding via calcineurin and the transcription factor NFAT, is a key player controlling the chemomigratory potential of developing GnRH-secreting neurons. Furthermore, our data highlight the "switch" nature of this phosphatase, whose activation or inactivation guides cells to proceed from one genetic program to the next.