![](https://www.endotext.org/wp-content/uploads/male/10/figure3.png)
Figure 3. Production of peptides for presentation on MHC receptors for T-cell recogntion. The 9-11 amino-acid peptides displayed by MHC class I receptor molecules on the cell surface are generally, but not exclusively, derived from endogenous proteins made by the antigen-presenting cell. A process called cross priming may also allow external proteins to be presented via the class I pathway.