This is based on the levels or amounts of various factors they secrete or release into the surrounding environment.55 Accordingly, Waterman et al, suggested a new type of MSCs in which MSCs-1 express toll-like receptor 4 (TLR 4), and exert antitumor activity, while, due to the expression of TLR3, MSCs-2 inhibit immune cell activity and support tumor growth.56 The investigations have shown that MSCs adopt a pro-inflammatory phenotype or characteristics in the presence of low levels of the IFN-γ and TNF-α. This evidence concerns the gene IFNG and neoplasm.