We have been studying biogenesis and function of organelles in eukaryotic cells using Arabidopsis as a model system. For this, we aim to understand how newly synthesized proteins are delivered to various organelles by direct targeting or trafficking. Our group has identified a large number of molecules involved in protein trafficking from the ER to various endomembrane compartments, and also from the cytosol to chloroplasts and mitochondria. Through these studies, we hope to get some insight into the evolution of chloroplasts and mitochondria. Another important topic is the role of ABA, the abiotic stress hormone, in abiotic stress responses and also in chloroplast homeostasis under the abiotic stress condition. In addition to these basic research topics, we actually spend half of our effort to biotech-related research. We are trying to apply the basic knowledge to developing plants as a new cost-effective and more widely applicable platform for the production of a wide range of recombinant proteins including protein drugs, vaccines, industrial enzymes, and etc.