CD4 and cancer: mTORC1 plays a key role in the regulation of autophagy by phosphorylating components of the autophagy-induction machinery.[12] Immunization of mice with purified tumor-derived autophagosomes was shown to induce tumor-specific T-cell responses.[13] For tumor cell invasion, regulatory T cells (Tregs) are known to play a key role in the metastatic escape of cancer cells from the antitumor effector T cells.[14] Rapamycin can enhance the expansion of CD4 Foxp3 Tregs and this can result in suppression of other CD4 T cell activities.[15]