Transcriptional activator involved in the development of insulin-producting beta cells in the endocrine pancreas (PubMed:11076772). May also be involved in specifying diencephalic neuromeric boundaries, and in controlling the expression of genes that play a role in axonal guidance. Binds to elements within the NEUROD1 promoter (PubMed:19759004). Interacts with OLIG2. Expressed in restricted areas of the developing CNS: the hindbrain and forebrain, and pancreas. Expressed during embryogenesis. The homeodomain is essential for interaction with OLIG2. Mutant embryos do not form any insulin-expressing cells in the pancreas throughout development, and instead accumulate incompletely differentiated beta cells (PubMed:11076772). Simultaneous knockout of NKX6-1 and NKX2-2 is not distinguable from the single NKX2-2 knockout (PubMed:11076772). Belongs to the NK-2 homeobox family.