CD4 and neoplasm: The tumor tissue sections were analyzed by IF staining and confocal microscopy imaging, which showed that treatments with PS-acet.-STAT3 peptide significantly decreased STAT3 activation (p-STAT3) in tumor cells and CD4+ T cells and increased the infiltration of CD69+ activated CD8+ T cells in metastatic B16 lung nodules (Figure 7B) (49).