The LIM homeobox transcription factor 1B (LMX1B) belongs to the LIM-homeodomain family. Members of this family are known to be important for pattern formation during development. LMX1B regulates mid-hindbrain patterning; LMX1B-null mice embryos have a severe reduction in the number of midbrain dopaminergic neurons compared to wild-type. While LMX1B appears to be important for both the development and the survival of dopamine neurons, the related LMX1A is crucial for the differentiation of these cells. However, LMX1A and LMX1B function cooperatively to regulated the proliferation, specification and differentiation of midbrain dopaminergic neuronal progenitors