GSTP1 and cancer: It has been demonstrated there are abnormal expression of genes, such as c-erbB-2, neu, P53, ras, INT2, HSTF1, bcl-2, c-fos and c-jun in various types of cancer, including GBC, and these genes not only correlate with drug resistance but also frequently regulate and co-amplify P-gp and GST-π genes (28–34).