When comparing T cell infiltration ratio, up‐regulation of both CD4+ T and CD8+ T cell infiltration were observed in the Mg‐CaCO3 group in the MC38 tumor model (CD4+ T: Ctrl: 15.88, Mg‐OPSZ: 11.95, Mg‐CaCO3: 46.33; CD8+ T: Ctrl: 24.33, Mg‐OPSZ: 21.63, Mg‐CaCO3: 34.85) with a significant decreased Treg ratio (Ctrl: 40.93, Mg‐OPSZ: 13.63, Mg‐CaCO3: 0.1875) (Figure 6i–l). The gene discussed is CD4; the disease is neoplasm.