CDKN2A and neoplasm: Finally, the role of p19, encoded by Cdkn2b, as a tumour suppressor in regulating pituitary anterior lobe proliferation has been revealed by a conventional knockout mouse model of Cdkn2b, as Cdkn2b−/− mice developed multiple tumour types including PRL, GH and FSH secreting pituitary adenomas (Bai et al., 2014).