Silencing of GCS by MBO-asGCS Represses MDR1 Expression and Reverses Tumor Resistance to Doxorubicin in vivo. (A) Tumor growth. Tumors generated from NCI/ADR-RES cells (~3 mm in diameter, 10 mice/group) were treated with MBO-asGCS (1 mg/kg every 3 days) or doxorubicin (2 mg/kg/week) and combination thereof. Data represent the mean ± SE; *, p < 0.001 compared to saline group (open squares); **, p < 0.001 compared to doxorubicin treatment (solid squares). (B) Western blots of tumor tissues. After treatments, extracted tumor proteins (100 μg/μl, three samples per group) were resolved by 4-20% SDS-PAGE and immunoblotted with anti-GCS or anti-P-gp antibodies, respectively. (C) Immunostaining. After retrieval, antigens on tissue sections (5 μm) were recognized by anti-GCS (green) and anti-P-gp (red) antibodies with fluorescence conjugated secondary antibodies. Microphotographs of merged fluorescence (Fluo.) with H&E staining (H&E) were originally magnified by 200.