CD4 and neoplasm: With this in mind, it will be crucial to understand how oncogenic events and anti-cancer therapies influence antigen processing, antigen presentation, and the pool of antigenic peptides that can be displayed on the cell surface of tumors via MHC molecules and detected by anti-tumor CD4- and/or CD8 T lymphocytes (Chang and Ferrone, 2007; Hastings, 2013).