The aims of this study were to (1) correlate Bcl-2 protein expression with gemcitabine resistance (GEM-R) in gastric, nasopharyngeal and breast cancer cell lines, (2) evaluate the combination of gemcitabine and gossypol in GEM-R cancer cell lines with high level of Bcl-2 expression and (3) determine the mechanisms involved in reversing gemcitabine resistance by gossypol. The gene discussed is BCL2; the disease is breast carcinoma.