APC and colorectal carcinoma: The tamoxifen-inducible Lrig1-CreERT2 driver facilitates the loss of 1 Apc allele in leucine-rich repeats and immunoglobulin-like domains 1–positive (Lrig1-positive) intestinal epithelial stem cells, and Apc loss of heterozygosity occurs in this model as in human CRC (35).