Relative amount of trastuzumab-specific CDR in tumor cell regions and non-tumor cell regions. (A) HE staining. Tumor regions (inside solid lines) and non-tumor regions (inside dashed lines) were dissected individually by LCM and collected. (B) The relative amount of trastuzumab-specific CDR. LC-MS/MS analysis revealed that the target peptide (DTYIHWVR, m/z 545.3 detected as a doubly charged ion) in tumor cell regions was 11-fold higher than that in non-tumor cell regions.