Figure 2.

Summary of UVB dose impact on relative cell viability as measured by the MTT assay. For the cells cultured in low calcium, UVB causes a statistically significant decrease in cell viability starting at 60 mJ cm⁻² versus their 0 mJ cm⁻² dose. For keratinocytes cultured in high calcium a statistically significant difference was observed at all UVB doses relative to the low calcium 0 mJ cm⁻² dose control (against which they were normalized), but no statistical difference was observed at all UVB doses when normalised to their own control (high calcium 0 mJ cm⁻² UVB). Comparisons made between keratinocytes cultured in high and low calcium at each UVB dose showed a statistical difference a 0, 20, and 40 mJ cm⁻² UVB (bar with *). Error bars represent standard error of the mean. Statistical comparisons were made using a Student’s t-test with *p < 0.05 and **p < 0.01. Data represent averages of keratinocyte cultures made from four different skin donors.