TP53 and neoplasm: Moreover, in agreement with our results in vitro (Fig 2F, 2G, 2K and 2M–2O), the tumors treated with brequinar had higher expression of p53 as well as the neuronal differentiation marker acetyl-tubulin (Fig 3G), which is supported by recent work showing that inhibition of the de novo pyrimidine synthesis pathway increases the differentiation of glioblastoma tumor cells [34, 35].