Figure 2 Effect of lutein on the viability of keratinocytes treated with UVB measured by MTT assay. Viability of keratinocyte cell line (A, B) and primary human keratinocytes (C, D) treated with 0.5 to 15 μM of silk lutein (A, C) or c-lutein (B, D) for 24 hours prior to irradiation with UVB at various doses ranging from 8 to 32 mJ/cm2. Each bar represents the percentage of cell viability. Error bars are one standard deviation. *, p < 0.05