0168-95251662000JunTrends GenetPositioning the isthmic organizer where Otx2 and Gbx2meet.237240237-40Regional diversity along the anterior-posterior axis of the central nervous system is established during gastrulation and is subsequently refined by local organizing centres that are located at genetically defined positions. The isthmic organizer possesses midbrain- and cerebellum-inducing properties, and its positioning at the midbrain-hindbrain boundary is a crucial event that controls midbrain and cerebellum development. Recent work has shown that two transcription factors, Otx2 and Gbx2, are instrumental in positioning the isthmic organizer at the midbrain-hindbrain boundary.SimeoneAAInternational Institute of Genetics and Biophysics, CNR, Via G. Marconi 12, 80125 Naples, Italy. simeone@iigbna.iigb.an.cnr.itengJournal ArticleReview