FOXJ3 (forkhead box protein J3) is a 622 amino acid protein encoded by the human gene FOXJ3. FOXJ3, having one forkhead DNA-binding domain, is a novel forkhead factor and, as such, belongs to the forkhead protein family. The HNF3/forkhead family includes a large number of transcription factors that share a structurally related DNA binding domain. Forkhead factors are known to play important roles both during development and in adults. FOXJ3 is expressed in neuroectoderm, in neural crest, and in many structures derived from neural crest cells, such as facioacoustic, trigeminal and dorsal root ganglia. Stripes of FOXJ3 expression appear in the location of myotomes and expand ventrally in a pattern similar to the developing body wall musculature. Developing limbs have a complex pattern of FOXJ3 expression that at E12.5 colocalizes with the condensed mesenchyme of the skeletal primordia.