TGFB1 and neoplasm: The slight improvement in tumor control with CD4+ T cell depletion over RT + 5FU alone (Fig. 1c) suggests that CD4+ T regulatory cells (Treg) may also be a target of LY leading to less inhibition of CD8α+ T cells, or may be a source of the TGFβ that inhibits CD8α+ T cells, such that CD4-depletion abrogates the immunosuppressive effects.