- Bartel F, Schulz J, Böhnke A, Blümke K, Kappler M, Bache M, et al. Significance of HDMX-S (or MDM4) mRNA splice variant overexpression and HDMX gene amplification on primary soft tissue sarcoma prognosis. Int J Cancer. 2005;117:469-75 pubmed..In summary, our data indicate that both the overexpression of the HDMX-S transcript as well as HDMX gene amplification are important prognostic markers for STS. ..