This book provides a state—of—the—art compendium on the role of proteoglycans and glycosaminoglycans during development and in cancer. It also suggests directions for novel therapeutic and biotechnological applications in stem cell biology. Proteoglycans and glycosaminoglycans, as part of the extracellular matrix, are multifunctional modulators of growth factor, cytokine, integrin and morphogen signaling, which determine both self—renewal, senescence and/or differentiation of stem cells during development. Since proteoglycans modulate cell adhesion and migration they are important organizers of the extracellular matrix within the proper stem cell niche. A malfunctioning of proteoglycans and glycosaminoglycans contributes to the cancer stem cell phenotype, which is linked to therapeutic resistance and recurrence in malignant disease. This book is essential reading for anyone interested in the extracellular matrix and its role in development. The series Biology of Extracellular Matrix is published in collaboration with the American Society for Matrix Biology.