Cyanazine exposure was associated with the formation of mammary-glandtumors in Sprague-Dawley rats (Bogdanffy MS, unpublished data); mechanismof action studies suggest that tumor formation is mediated througha prolactin mechanism thought to be of low relevance to the developmentof human breast cancer (Bogdanffy et al. 2000). The gene discussed is PRL; the disease is breast cancer.