PEAR1 and neoplasm: However, consistent with all the previous mouse models, there was an increased lung metastatic burden in EC-Pear1-KO mice indicated by an increase in the mCherry epifluorescence IVIS signal (Fig. 5E and F), increased total tumor cell count in the lungs (Fig. 5G) and an increased Ki67 proliferative index of tumor cells in the lungs (Fig. 5H and Suppl.