evidence: Cancer vaccines based on messenger RNA have been the subject of recent, in-depth last investigations [2]. Figure 6 illustrates the process of how mRNA vaccines work to activate the immune system. When the mRNA vaccine is introduced into the body, it is taken up by cells through endocytosis and released from the endosome. Ribosomes then convert the mRNA into proteins that stimulate the immune system in two main ways: i) proteasomes break down the proteins into peptides, which are displayed as antigens on the cell surface by MHC class I molecules, subsequently activating CD8 + T cells that release perforin and granzyme to destroy infected cells; ii) proteins secreted externally are absorbed by APCs and broken down into peptides, which are displayed on the cell surface by MHC class II molecules, allowing recognition by CD4 + T cells, which in turn activate cellular immune responses by producing cytokines and humoral immune responses by co-activating B cells. Furthermore, single-stranded RNA and double-stranded RNA in mRNA vaccines bind to TLR in the endosome, initiating antiviral innate immune responses through the production of type-I interferon (IFN-I).