UNIT 4.38 CYP1B1 Detection

  1. Rao L. Divi1,
  2. Andreas Luch2,
  3. Mukesh Verma1,
  4. Brinda Mahadevan3

Published Online: 1 FEB 2012

DOI: 10.1002/0471140856.tx0438s51

Current Protocols in Toxicology

Current Protocols in Toxicology

How to Cite

Divi, R. L., Luch, A., Verma, M. and Mahadevan, B. 2012. CYP1B1 Detection. Current Protocols in Toxicology. 51:4.38:4.31.1–4.31.26.

Author Information

  1. 1

    Methods and Technologies Branch, Division of Cancer Control and Population Sciences, National Cancer Institute, NIH, Bethesda, Maryland

  2. 2

    German Federal Institute for Risk Assessment, Berlin, Germany

  3. 3

    Global Occupational Toxicology, Abbott Laboratories, Abbott Park, Illinois

Publication History

  1. Published Online: 1 FEB 2012
  2. Published Print: FEB 2012


This unit describes procedures for measuring CYP1B1 gene expression by reverse transcription real-time PCR (qRT-PCR), CYP1B1 protein levels by western blotting, and CYP1B1 enzyme activity through conversion of 7-ethoxyresorufin substrate. To achieve specific measurement of CYP1B1 activity in the presence of CYP1A1 and CYP1A2, CYP1B1 inhibition and a subtractive approach have been adopted. 2,4,3′,5′-Tetramethoxystilbene (TMS) is a potent and selective competitive inhibitor of CYP1B1 with an IC50 of 3 nM for EROD and ∼90 nM for E2 4-hydroxylation. Binding studies with purified CYP1B1 suggests that TMS interferes in the proximity of the heme region of CYP1B1 with high affinity. Compared to other potent inhibitors such as α-naphthoflavone, which is a known CYP1 family inhibitor with no selectivity between CYP1B1 and CYP1A2, TMS is ∼50- and 520-fold selective for inhibition of CYP1B1 when compared to CYP1A1 and CYP1A2, respectively. Thus, TMS can serve as a helpful chemical scalpel for dissecting CYP1B1 activity from the overall activity of CYP1 family members against ethoxyresorufin. Curr. Protoc. Toxicol. 51:4.38.1-4.38.26. © 2012 by John Wiley & Sons, Inc.


  • cytochrome P4501B1;
  • quantitative gene expression;
  • CYP1B1 enzyme activity;
  • western blotting;
  • CYP1B1 inhibition