FAP and neoplasm: Thesetumors show a moderately well-differentiated morphology organizedin glandular structures which are typical for adenocarcinomas, andboth collagen as well as FAP-expressing cells are abundantly presentin the tumor stroma.42 The subcutaneousinjection of tumor cells leads to highly controlled tumor growth thatis easy to monitor, and exposure of the tumor to light can be donesuperficially through the skin, making this model easier to use thanorthotopic models.