PCNA and neoplasm: The study of U87 and T98G control tumors did not reveal any differences in the frequency of invasion into the chick embryo chorioallantoic membrane (CAM), the expression of neo-angiogenesis in the CAM mesenchyme beneath the tumor, or the expression of proliferating cell nuclear antigen (PCNA) and polycomb inhibitory complex catalytic subunit 2 (EZH2) in the tumor.