Furthermore, at 3 weeks after the tail vein injection conducted with a hydrodynamics-based procedure [25, 26], compared to the control mice, the mice injected with midkine-knockdown cells had a significantly greater number of tumor foci on the surface of liver (p < 0.01) plus lung (p < 0.05) (Figure 4B and 4C), and a longer survival time (Figure 4D, p = 0.011). Here, MDK is linked to neoplasm.