PTTG1 and neoplasm: Thus, the vascular endothelial growth factor (VEGF) has a pivotal role in tumor angiogenesis, Endolin (CD105, CD31) has a role in microvascular density, the pituitary tumor-transforming gene (PTTG) and fibroblast growth factor (FGF) are involved in pituitary tumorigenesis and development, while the Ki67 proliferation marker has a role in cell proliferation [105].