CD4 and neoplasm: The immunomodulatory actions of CD73 and adenosine and their contribution to tumor immune escape include for example inhibition of CD4+ and CD8+ T cells, natural killer cells and antigen-presenting dendritic cells as well as the induction of immunosuppressive cells such as Treg, myeloid-derived suppressor cells (MDSCs), and macrophages with alternative M2 like activation state that have been extensively summarized elsewhere [103,323,324,325,326] and will therefore not be discussed in more detail here.