The WNT signal transduction cascade is a main regulator of development throughout the
animal kingdom. Wnts are also key drivers of most types of tissue stem cells in adult
mammals. Unsurprisingly, mutated Wnt pathway components are causative to multiple
growth-related pathologies and to cancer. Here, we describe the core Wnt/β-catenin
signaling pathway, how it controls stem cells, and contributes to disease. Finally, we discuss
strategies for Wnt-based therapies.