CD4 and neoplasm: Quantification of tumor-infiltrating T cells by flow cytometry showed that the number of total T cells (CD45+ CD3e+), CD4+ T cells and cytotoxic CD8+ T cells, including those producing the cytolytic protease granzyme B, were significantly increased in tumors from mice treated with PTP 9 compared with those treated with the DMSO (Fig. 3D and E).