SOX2+ lineage tracing (allowing to follow the SOX2+ cells as well as their progeny over time) showed that the mutant β-catenin-expressing SOX2+ cells did not directly give rise to the ACP tumor, but induced the tumor and promoted the proliferation of the surrounding (tumor) cells (Table 1), most likely via the production of paracrine factors belonging to key (stemness) pathways (such as WNT; sonic hedgehog, SHH; fibroblast growth factor, FGF; bone-morphogenetic protein, BMP) (3, 32). Here, SHH is linked to neoplasm.