In contrast, bortezomib-treated rats showed a decreased number of peritoneal adhesions, decreased values of ubiquitin and the 20S proteasome, NFkB, IL-6, TNF-α, and increased levels of IkB-beta in the adhered peritoneal tissue.The UPS system, therefore, is primarily involved in the formation of post-surgical peritoneal adhesions in rats. This evidence concerns the gene IL6 and peritoneal well differentiated papillary mesothelioma.