Figure 4.

The cytotoxic effects of GrB/scFvMEL on the gp240 antigen-positive melanoma cell lines. Samples (GrB/scFvMEL or MEL sFv/rGel) were assayed using a standard 72-hour cell proliferation assay with melanoma cell monolayer and using crystal violet staining, as described under Materials and Methods. Percent control refers to the percentage of cells in drug-treated wells compared to that of control (untreated) wells. A 50% growth-inhibitory effect (IC₅₀) was calculated. The bar chart showed the IC₅₀ value of GrB/scFvMEL in different melanoma cell lines. GrB/scFvMEL demonstrated cytotoxic effects on A375-M, MEL526, and TXM-18L, which expressed high-level gp240 antigen. However, no cytotoxic effects on TXM-1 cells were found at doses of up to 1 µM.