CDKN1B and pancreatic adenocarcinoma: Finally, to confirm the direct role of p27 in the control of Sox9 transcription, we performed chromatin immunoprecipitations (ChIP) in various cell lines, including the pancreatic adenocarcinoma cell line PANC1, using p27 antibodies used previously [37, 43, 44] or isotype control antibodies, followed by PCR for the Sox9 promoter sequence.