This gene encodes a homeobox-containing protein that belongs to the NK-2 homeobox family. This protein is a vertebrate homolog of Drosophila homeobox-containing protein called 'tinman', which has been shown to be essential for development of the heart-like dorsal vessel. In conjunction with related gene, NKX2-5, this gene may play a role in both pharyngeal and cardiac embryonic development. Mutations in this gene are associated with persistent truncus arteriosus.[provided by RefSeq, Aug 2011].