TP53 and neoplasm: However, with increasing evidence that MDM2 has p53-independent roles we, therefore, wanted to investigate the status of MDM2 in tissue sections of p53flox/flox; Ptenflox/flox LPS tumors.7, 8 We investigated MDM2 RNA levels by real-time PCR (Taqman) in normal versus tumor tissue but did not see an appreciable difference between normal fat and tumors (1.5- to twofold, data not shown) as seen in human LPS samples.24 Therefore, we examined the protein expression of MDM2 by immunohistochemistry.