Achievements of the research group are important and top-level also according to the international standards. In the last five years our contribution to the understanding of the role of lysosomal cysteine proteases and their inhibitors in proteolysis was significant. Important discoveries were so made in the fields of structure-function relationship of proteases and of proteolysis regulation. In this period we have, for example, identified a possible mechanism, which explains the involvement of lysosomal cysteine proteases in apoptosis progression. These are pioneering studies in this field and the article, where the work was published, has been cited over 150 times since the appearance in 2001, indicating high relevance and competitiveness of our research. Another important finding opening new areas in apoptosis research is the discovery that the inhibitors, which were believed to be caspase-specific, inhibit also lysosomal cysteine proteases. In addition, new studies on thyroglobulin type 1 domain proteins, such as the MHC class II invariant chain and equistatin, open new aspects of cysteine protease regulation in a number of processes, including antigen processing and presentation in the case of invariant chain or pest suppression in the case of equistatin from A. equina. New findings on cathepsin C are also very important both from structural and medical point of view. The same is true also for the studies on cancer, demonstrating that lysosomal cathepsins can be used as diagnostic markers in certain types of cancer. In this period we have published several articles in journals with IF biger than 10.0, which is within the upper 5% of journals in this highly competitive area of research. As a consequence, these works are highly cited with the program leader having over 8000 citations (over 500 new citations annually within last three years), whereas all coworkers have been cited over 15000 times. These include works published within the last five years period, which have been frequently cited as well (over 550 citations for the works of program leader). On this basis, the program coworkers have been frequently invited as invited speakers at international conferences or at foreign universities and organized numerous international symposia in Slovenia. Program coworkers have also important functions in the international expert societies and are members of editorial boards of renowned international journals. This international reputation as a consequence of high quality publications resulted also in numerous successful collaborations with leading scientists from many respectable international institutions.