For instance, some tumor cell types [221], i.e., some cancer cells, effector T cells (CD8pos), regulatory T cells (CD4pos, CD25pos), tumor endothelial cells, Myeloid-derived suppressor cells (MDSC), Monocyte-derived human macrophages (MDM), Cancer-associated fibroblasts (CAF), Cancer stem cells (CSC), are able to express CD95L at the membrane, thus conferring the tumor environment a “counterattack” mechanism involved in the elimination of tumor-infiltrating lymphocytes and prevention of successful immunotherapy [222–228]. This evidence concerns the gene FASLG and cancer.