HLI373 (3-15 μM; 15 hours) selectively kills tumor cells expressing wild type p53 [1]. HLI373 (10-50 μM) stabilizes cellular Hdm2 in a dose-dependent manner. HLI373 (3 μM) activates p53 transcription [1]. HLI373 selectively inhibits auto-ubiquitylation of Hdm2 [1]. Co-transfection with plasmids encoding p53 and Hdm2 results in degradation of p53. Incubation with HLI373 (5-10 μM; 8 hours) blocks p53 degradation. HLI373 increases p53 and Hdm2 protein levels in cells [1]. HLI 373 also shows lower IC 50 values (below 6 μM) against both chloroquine-sensitive P. falciparum D6 strain ( Pf D6) and chloroquine-resistant P. falciparum W2 strain ( Pf W2) and exhibits early growth inhibition [2]. HLI-373 is a MDM2 inhibitor interrupting its ubiquitin E3 ligase activity, could abolish the ubiquitylation of its substrate protein p53. HLI-373 targets the C-terminus functioning as an E3 ubiquitin ligase [3]. Cell Viability Assay [1] Cell Line: Wild type p53 mouse embryo fibroblasts (MEFs), and p53-deficient MEFs Concentration: 3, 10, 15 μM Incubation Time: 15 hours Result: Increased cell death in wild type p53 MEFs in a dose-dependent manner, p53-deficient MEFs were relatively resistant. Western Blot Analysis [1] Cell Line: U2OS cells Concentration: 5, 10 μM Incubation Time: 8 hours Result: Blocked p53 degradation caused by co-transfection with plasmids encoding p53 and Hdm2.