MKI67 and keratoconus: The reduced area occupied by mucinous neoplastic lesions was attributed to lower proliferation, measured by Ki67 immunohistochemistry (IHC) in the KC;Sirt1-lox background compared to KC controls (60 ± 13 versus 104 ± 13 counts of Ki67 positive cells per field, n = 9–13, P < 0.05, Figure 1E, 1F).