Previous studies demonstrated that DEX blocks neural cell proliferation by inducing arrest in the G1 phase of the cell cycle.41, 43 As depicted in Supplementary Figures S3F and G, withdrawal of DEX from hippocampal NPC cultures alters the expression of two key regulators of the cell cycle, cyclinD1 (up-regulated) and p27 (down-regulated). This evidence concerns the gene CCND1 and nasopharyngeal carcinoma.