PBX/Knotted 1 Homeobox 1 (PKNOX1) is a protein that in humans is encoded by the PKNOX1 gene.

An important paralog of this gene is PKNOX2.

PKNOX1 belongs to the three amino acid loop extension (TALE) class of homeodomain transcription factors that form transcriptionally active complexes involved in development and organogenesis. PKNOX1 is essential for embryogenesis, but it can also act as a tumor suppressor in adulthood.

This article incorporates text from the United States National Library of Medicine, which is in the public domain.