KLLN and neoplasm: Thus the recombinant therapeutic fusion protein included (1) Killin as cytostatic/cytotoxic component, (2) XTEN for long blood circulation time, deactivation of Killin and passive targeting of the tumor by exploiting the EPR effect, (3) an MMP2/9 cleavage site for specific activation in the tumor, and (4) a CPP to transfer Killin into the cells.