The invention relates to a method of identifying the epithelial-mesenchymal transition of mesothelial cells (EMTMC) and identifying EMTMC-modulating compounds, pharmaceutical compositions and use thereof in the diagnosis and treatment of diseases associated with EMTMC. The inventive method is based on the fact that mesothelial cells play an active role in the structural and functional alteration of the peritoneum during peritoneal dialysis which leads to the epithelial-mesenchymal transition which in turn causes ultrafiltration failure. The aforementioned findings demonstrate a series of targets and markers which are intended for the development of novel peritoneal dialysis solutions, for the monitoring of patients undergoing said treatment and for the treatment of diseases associated with functional alterations to the mesothelium.