CD4 and neoplasm: The tumor and its microenvironment are composed of a network of tumor cells, stromal cells (such as carcinoma-associated fibroblasts), endothelial cells and tumor-infiltrating immune cells including CD4+ and CD8+ T cells, regulatory T cells (Tregs), tumor-associated macrophages, natural killer (NK) cells, and myeloid-derived suppressor cells (MDSC), in addition to soluble factors like chemokines, cytokines, and growth factors like vascular endothelial growth factor (VEGF) [2,5,6,7].