It was found that the cytotoxicity of splenocytes to B16F10 target cells at 25:1 ratio was notably enhanced (61±2.6%) in mice immunized with the tumor vaccine B16F10/GPI-IL-21 in contrast to mice immunized with the B16F10 cells (23±2.8%), and the difference was statistically significant (P = 0.0003). Here, IL21 is linked to neoplasm.