CDKN2A and keratoconus: Whereas p19ARF mRNA expression is induced in PDECs isolated from pre-malignant stages from KC mice, no mRNA expression was detected in murine PDAC cancer cell lines (Supplementary Fig. S1c), demonstrating the important tumor suppressive function of Cdkn2a for murine PDAC development and showing that the Cdkn2a barrier is not conquered in PDECs isolated at pre-malignant stages.