ACVRL1 and neoplasm: All correlations were confirmed in mouse PanNETs from RIP1-TAg2 mice, where expression of Acvrl1 and Eng was found to be highest during the angiogenic phase of tumor development, compared to pre-malignant lesions (normal or hyperplastic islets), primary tumors (islet tumors or metastasis-like primary tumors), or hepatic metastases (Figure 1E–1H).