LAUSR

p27Kip1 functions to coordinate cell cycle progression through the inhibition of cyclin‐dependent kinase (CDK) complexes. p27Kip1 also exerts distinct activities beyond CDK‐inhibition, including functioning as a transcriptional regulator. The aryl hydrocarbon receptor (AhR) is a ligand‐activated transcription factor with diverse biological roles. The regulatory inputs that control AhR‐mediated transcriptional responses are an active area of investigation. AhR was previously established as a direct regulator of p27Kip1 transcription. Here, we report the physical interaction of AhR and p27Kip1 and show that p27Kip1 expression negatively regulates AhR‐mediated transcription. p27Kip1 knockout cells display increased AhR nuclear localisation and significantly higher expression of AhR target genes. This work thus identifies new regulatory cross‐talk between p27Kip1 and AhR.