- No effect of CYP1B1 Val432Leu polymorphism on CYP1B1 messenger RNA levels in an organochlorine-exposed population in Slovakia. van Duursen, M.B., Fernández Cantón, R., Kocan, T., Sanderson, J.T., Kieviet, K., van den Berg, M. Cancer Epidemiol. Biomarkers Prev. (2005)