IGF1 and lung carcinoma: Lastly, using the RNAi-resistant Trop2 cDNA as a template, we constructed Trop2 mutants harboring a deletion in either the EGF-like or thyroglobulin type-1 domains present in the extracellular region, both of which are required by Trop2 to bind IGF-1 in lung cancer cells [10].