To better understand the molecular mechanisms underlying tumor resistance to regorafenib, a multi-kinase inhibitor currently used in CRC patients, mouse colon organoid lines were established from tamoxifen-treated VilCreERT2/Apc+/+ and VilCreERT2/Apcfx/fx mice, generating colonoids and tumoroids, respectively. The gene discussed is APC; the disease is neoplasm.