the current volume represents the fourth over a period of five years in the series on advances in the cellular and molecular biology of breast cancer. throughout this series, a broad view has been taken at what are cutting edge topics in the basic research into breast cancer. since the last volume, research in breast cancer has continued to proceed at an explosive rate, and the current volume will provide the reader with some of the excitement felt by the editors and authors. the first section is devoted to the basic process of proliferation, differentiation, and malignant progression of breast cancer. the second section emphasizes the genetic basis for breast cancer onset and malignant progression. the third section deals with growth factors, receptors, and polyamines in proliferation mechanisms. the fourth section is devoted to aspects of metastases and tumor-host interactions. the final section presents recent studies on rodent models of breast cancer.