PDX1 and keratoconus: We quantified levels of Ki67 in Pdx1-Cre, KrasG12D/+ (KC) and Pdx1-Cre, KrasG12D/+, Lkb1flox/+ (KLC) PanINs and confirmed that Ki67 expression was elevated significantly in Pdx1-Cre, KrasG12D/+, Lkb1flox/+ (KLC) PanINs, compared with Pdx1-Cre, KrasG12D/+ (KC) PanINs (median % Ki67-positive cells: KC = 10.4, KLC = 79.9; P = .0006, data not shown).