Figure 3. Retinol activation into retinoic acid in corneal epithelial cells

Corneal epithelial cells were transiently transfected with a retinoic-responsive CAT reporter gene (DR5-tk-CAT). CAT production was determined after 24 h incubation and normalized to β-galactosidase activity. The value of CAT induction was arbitrarily set at 100 for controls. Each value represents the mean±SD of 10 experiments. The left panel indicates inhibition by different toxins for activation of retinol into retinoic acid. Asterisks, the double asterisk, and the sharp (hash mark) indicate statistical differences between the different incubation conditions tested (p<0.05).