Trastuzumab and single hinge cleaved trastuzumab tumor inhibition efficacy in breast cancer xenograft mouse model. (A) BALB/c nu/nu mice (n = 5) were subcutaneously inoculated with 5×106 BT474 human breast cancer cells. Mice were treated with the antibodies at 5 mg/kg weekly for a total of five doses when tumors reached an average size of 100 mm3. Tumor sizes were measured and compared among the treatment groups. *P < 0.05 and **P < 0.005. (B) Tumor lysates were prepared from the frozen xenograft tumor tissues. Total HER2 expression, pHER2 (Y1248), pAKT (S473), and pErk1/2 were determined by western blotting. scIgG-T, single hinge cleaved trastuzumab.