This was the second meeting held at the Jackson Laboratory devoted to developing improved preclinical mouse models for breast cancer. The previous meeting was held in October of 1997, and there has been substantial progress made in the field in the past 2 years. This year's meeting was preceded by a workshop coordinated by Gertraud Robinson [National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), National Institutes of Health, Bethesda, Maryland, USA] designed to provide hands-on training in the many specialized techniques that have been developed to study the development of the mouse mammary gland. These biologic techniques, coupled with the use of transgenic and knockout mouse models, provide a powerful approach to dissect the mechanisms by which specific genes regulate normal mammary gland development and to identify the genetic alterations that are involved in the initiation and progression of breast cancer. Robert Cardiff (University of California at Davis, California, USA) also ran a pathology tutorial that discussed the consensus terminology and recommendations of a group of pathologists from a National Cancer Institute sponsored workshop held in Annaopolis, Maryland, USA in March 1999, entitled 'Comparative Pathology of Animal Models for Mammary Cancer'. Representative histology images can be accessed at http://mammary.nih.gov/atlas/histology/jaxworkshop/index.html.
The Keynote Address by Charles Daniel (University of California at Santa Cruz) provided an excellent historic perspective on the development of the normal mouse mammary gland and the pioneering efforts of a number of investigators at the Cancer Research Genetics Laboratory at the University of California at Berkeley who helped develop these techniques, which are so important for studying mammary gland biology. In addition, he emphasized the areas that require increased study in the future. These include studying the development of the embryonic mammary gland, developing techniques to manipulate the mammary stroma, incorporating information learned from other model systems such as Caenohabditis elegans and Drosophila into mammary gland biology, and finally investigating the biology of mammary stem cells and cell senescence. This year's meeting was especially timely because it coincided with a program just initiated by the US National Cancer Institute: The Mouse Models of Human Cancer Consortium.