Of note, this resumption of proliferation was clinically significant, because lesions with continued tamoxifen treatment were localized with no evidence of brain tissue invasion (Fig. 5D, middle), while those with tamoxifen withdrawal showed tumor invasion into brain parenchyma (Fig. 5D, right), similar to vehicle-treated lesions where p53 was never restored (Fig. 5D, left). This evidence concerns the gene TP53 and neoplasm.