To test whether the accumulation of MDSCs caused by constitutive exposure to PS on the outer leaflet of the cell membrane of sgATP11b-545 cells in primary tumors creates a stronger immunosuppressive signal for cancer metastasis, we studied the proliferation of T cells isolated from the spleen of WT mice, stimulated with CD3/CD28, and cocultured with MDSCs. The gene discussed is CD28; the disease is cancer.