CD99 and soft tissue sarcoma: Downregulated CD99 was also identified in several human bone and soft tissue sarcoma subtypes.<h4>Conclusions</h4>Proteomics investigation of a MSC-transformation model of sarcoma has yielded ALDH1A3 and CD99 as potential targets for sarcomagenesis that may contribute to a greater understanding of the disease and the development of novel therapeutic approaches.