Non-rodent animals also hold irreplaceable value in CRC metastasis and drug resistance research: analysis of dog CRC identified three distinct tumor infiltration patterns, enabling the reclassification of human CRC genomic data into corresponding subtypes and revealing previously unrecognized disease heterogeneity [115], rabbit liver metastasis models help elucidate the formation of the liver niche microenvironment in CRC [112]; while UPP1 mutant C. elegans have become a crucial platform for studying 5-fluorouracil resistance mechanisms [84]. The gene discussed is UPP1; the disease is colorectal carcinoma.