AQP4 and adenocarcinoma: Of the 9 genes, 5 are known to be potentially linked to adenocarcinoma histology: NK2 homeobox 1 (NKX2-1), aquaporin 4 (AQP4), Chromosome 16 open reading frame 89 (C16orf89), napsin A (NAPSA), and surfactant protein B (SFTPB).