CD4 and cancer: MOF-gated MS showing a slow release of encapsulated cancer antigens and immunopotentiators in a neutral environment and a rapid release in an acidic environment will greatly promote the delivery of cancer antigens and immunopotentiators to pivotal APCs, the activation and trafficking of APCs to nearby tumour-draining lymph nodes, the presentation of digested fragments to naïve T cells, the clonal expansion of immune cells such as CD4+ and CD8+ T cells, the cytokine secretion to gain helper functions and thus the eradication of tumour cells.