Figure 9.

Expression of Tyrp1 correlates with increased melanoma sensitivity to 4-TBP. IIB melanoma cells, which lack functional Tyrp1, were transfected with an empty vector (IIB), functional Tyrp1 (IIB-Tyrp1), mutant Tyrp1 (IIB-Tyrp1–110), and functional tyrosinase (IIB-Tyr). Stable lines were generated and expression confirmed. Cells were then treated with either 100 or 250 μmol/L 4-TBP for 48 hours and the viability relative to cells treated with vehicle alone determined. Although there was no statistical difference in viability of cells exposed to 100 μmol/L 4-TBP, overexpression of Tyrp1 causes significantly increased sensitivity to 250 μmol/L 4-TBP compared with overexpression of either tyrosinase or the mutant form of Tyrp1 (Student’s t-test between lines treated with 250 μmol/L 4-TBP, P < 0.01, indicated by *). Error bars indicate SD.