LRIG1 and colonic neoplasm: Finally, lineage tracing studies demonstrate that loss of one allele of tumor suppressor Apc in Lrig1+ colonic progenitors42 and activation of oncogenic β-catenin in Lrig1+ epidermal cells43 led to formation of colon tumors and trichoadenomas, respectively, suggesting that Lrig1+ epithelial stem/progenitor cells can act as a cell-of-origin for tumorigenesis.