MHC-I antigen presentation is a critical surveillance mechanism used by the immune system to monitor the status of cells by generating and displaying on the cell surface peptides derived from the proteome. Antigenic peptides such as those generated by transformed cells and viruses would get presented on the cell surface in the form of peptide: MHC I complex for recognition and killing by CD8 T-cells. Methods to increase MHC I antigen presentation could enhance such immunity. Moreover, to avoid detection by CD8 T-cells, cancers and viruses have developed many evasion strategies to inhibit various steps in the MHC I antigen presentation pathway and methods to counteract these immune evasion mechanisms could be useful. Therefore, it is important to understand how MHC I levels are controlled and the strategies that can be used to enhance the expression of MHC I. In this dissertation, I will discuss how the HIV protease inhibitor, nelfinavir can enhance surface MHC I expression in various cell lines including cancer cells by blocking the ability of MHC I to undergo the ER associated degradation pathway (ERAD) and therefore, preventing MHC I molecules from translocating from the ER to cytosol for proteasomal degradation.