DLL1 and neoplasm: On the other side, although the recognized role played by Notch signaling in OS pathogenesis (McManus et al., 2014; Tao et al., 2014) and multidrug resistance (Ma et al., 2013; Pu et al., 2017), it has not been established yet whether the underlying mechanism involves exclusively a tumor cell autonomous activation of Notch mediated by the high Dll1 level or if it may include also an increased Notch activity in the surrounding cells.