Cells present in the tumor microenvironment are cancer associated fibroblasts (CAFs), endothelial cells, pericytes and immune cells, among which macrophages, dendritic cells (DCs), natural killer cells, mast cells (MCs), granulocytes, B cells and naïve and memory T cells [including cytotoxic CD8+ T cells and different subsets of CD4+ T and regulatory T cells (Tregs)]. The gene discussed is CD4; the disease is neoplasm.