Expression of CYP1B1 protein in healthy and malignant tissue. (A) Expression of CYP1B1 in human tumors detected by immunohistochemistry using a polyclonal antibody. All tissues were also stained with an immunoglobulin control (upper left panel and data not shown). (B) Western blot analysis of microsomal fractions (30 μg per sample) from healthy and malignant tissue using the monoclonal CYP1B1 antibody (similar results were obtained using the polyclonal antibody). Healthy and malignant lung tissue samples were from the same patient; healthy and malignant breast tissue samples were from 2 persons. As a positive control, 0.015 pmol rhCYP1B1 was loaded.