This manuscript describes a novel cell culture system to produce biologically active proteins, such as WNTs, which have potent stem cell activities. The system allows high levels of production of these proteins and will make them more readily available to the scientific community. The papers also elucidate important differences in activities amongst the various WNT proteins, with some acting at long distances and others acting at short distances. The transgenic cell lines will make the use and application of WNT proteins more commonplace and affordable.