Expression pattern of surface antigen and differential susceptibility to anti-neu antibody in TUBO and TUBO-P2J cell line. A) Microscopic images of TUBO and TUBO-P2J cells. B) Differential expression of MHC class I molecule, H-2Dd expression of TUBO and TUBO-P2J cells analyzed by flow cytometry is shown (left histogram). Representative analysis of H-2Kq and H-2Kd expression intensity in TUBO-P2J cells is shown (right histogram). The isotype control is represented by the gray shaded region and MHC class I molecule expression is represented by the black line. Data shown in each panel are representative of three independent experiments. C, D) Rat Neu protein expression of TUBO and TUBO-P2J cells were evaluated with flow cytometry for surface expression (C) and western blot for total protein level (D) using purified ascites of 7.16.4 and PE- or HRP-conjugated anti-mIgG. E) Inhibition of cell viability by treatment with anti-neu antibody (left graph). Cells were treated with anti-neu antibody (clone 7.16.4) and then cell viability was measured using the Premix WST-1 cell proliferation assay system. The assay was performed in quadruplicate with essentially similar results. Cell viability was recorded as the optical density at 440 to 600 nm relative to that of the sample not treated (mean ± SD). F) Therapeutic effects of anti-neu antibody on TUBO (left) or TUBO-P2J (right) bearing mice. WT BALB/c mice (n = 4-6/group) were inoculated s.c. with 4 × 105 TUBO cells or 2 × 105 TUBO-P2J cells and treated i.p. with 200 μg anti-neu (α-neu) antibody or isotype control (Ctrl) on day 12 and 100 μg antibody at 7 days after first treat. The growth of tumor measured once or twice a week. Data shown in each panel are representative of two independent experiments.