Expression of chemokine receptors on MSC membrane (e.g., chemokine receptor 4) is influenced by the features of tumor microenvironment (hypoxia and TNF-α), which makes such cytokine/receptor pair reactions more specific for MSC migration to the tumor site (Ponte et al., 2007; Kidd et al., 2009; Otsu et al., 2009). This evidence concerns the gene TNF and neoplasm.