TP53 and neoplasm: This evidence is in line with the increase in the amounts of p53 in the presence of elevated levels of MDM2 protein observed in DDLPS cells exposed for 10 h to 0.4 μM of QN-302 (Fig. 3B) and further supports the pivotal role of p53 in stimulating the expression/accumulation of MDM2, according to the tumour promoting nature of the MDM2-p53 pathway in tumours characterized by MDM2 amplification and bearing the wild-type form of p53.