To investigate the involvement of these detoxifying enzymes in the drug resistance of melanoma, an inducible (Tet-On system) antisense (AS) RNA strategy was used to specifically inhibit GSTP1 expression in A375 cells, a human melanoma cell line expressing high levels of GSTP1 and MRP1.
Analysis of the expression of another membrane transport protein, the multidrug-resistance-related protein (MRP1), showed that it was present in the cytoplasm of all the melanoma cell lines examined.