In vitro studies indicate that progesterone promotes cell proliferation in astrocytomas, as well as the expression of genes that are important for tumor growth and dissemination, e.g., cyclin D1, epidermal growth factor receptor (EGFR) and vascular endothelial growth factor (VEGF) 35,36. Here, CCND1 is linked to astrocytoma (excluding glioblastoma).