Su et al. [35] found that shikonin inhibited tumor growth and prolonged the survival of H22 and S18 hepatoma tumor-bearing mice, partly due to the recovery of CD3+ and CD19+ T lymphocyte numbers, enhanced NK cell activity and lymphocyte transformation, and increased IL-2 production in vivo. Shikonin can also protect immune system-related organs against tumor-induced damage and restore impaired immune function elicited by combined 5-FU administration. This evidence concerns the gene IL2 and neoplasm.