CXCR4 and sarcoma: As previously revealed data were achieved using animal model, sarcoma cell lines and molecular evaluation (Walter et al., 2014; Zhang et al., 2013; de Nigris et al., 2008; Fan et al., 2008), our study has been more focused on the protein expression levels of two CSC markers CD133 and CXCR4 using immunohistochemical detection in the human OS tissues.