Aberrant transcriptional activation may be involved in upregulation of mouse double minute homolog 4 (MDM4) in human HCC. (A) Relative MDM4 mRNA expression in human hepatocellular carcinomas (HCCs) with balanced (n = 13) and gained MDM4 (n = 24) gene loci, respectively. Mann–Whitney U test: p > 0.05. (B) An in silico analysis of the basal MDM4 promoter region identified putative transcription factor binding sites for serum response factor (SRF), ELK1, and ELK4. (C) Expression profiling revealed a positive association between MDM4 mRNA and the expression level of the putative transcription factors SRF, ELK1, and ELK4 in human HCC samples (n = 37). (D) MDM4, SRF, and ELK4 mRNA levels were associated with the survival probability of HCC patients in a second cohort (n = 32). Each median expression level was used for stratification. Abbreviation: n.s., not statistically significant.