LHX1 (LIM1) is initially expressed throughout the intermediate mesoderm but then becomes restricted to mesonephric ducts and tubules of the renal lineage (inferred from mouse embryos in Barnes et al. 1994, Fujii et al. 1994, Kobayashi et al. 2005). LHX1 is one of the key inducers of kidney development and retinoic acid acting via HOXB4 activates LHX1 expression, can induce kidney formation, and thus determines the position of the kidney on the rostral-caudal axis (inferred from chicken embryos in Preger-Ben Noon et al. 2009). HOXA6 represses LHX1 and therefore places a caudal limit on kidney development (inferred from chicken embryos in Attia et al. 2012). Mice lacking Lhx1 fail to form nephric ducts and kidneys (Shawlot and Behringer 1995, Tsang et al. 2000, Kobayashi et al. 2005). PAX2 and PAX8 appear to act redundantly to maintain LHX1 expression in the intermediate mesoderm and the nephric duct (inferred from mouse homologs), however PAX2 is expressed more widely in developing nephrons than PAX8 (Kaku et al. 2017).