SRF and hepatocellular carcinoma: Furthermore, MDM4 mRNA expression was significantly upregulated in neoplastic lesions from SRF-VP16iHep mice compared to their corresponding controls (normal liver 0.13 ± 0.07 vs. HCC 1.51 ± 0.66 (mean ± SEM), Wilcoxon test p < 0.01), confirming that SRF activates MDM4 transcription and results in an upregulation of MDM4 in vivo.