Furthermore, we aimed to investigate the role of increased extracellular phosphate in regulating proliferation, apoptosis, and expression of genes related to TGF-β1 signalling and ECM production in isolated FPTEC from cats without azotaemia and feline cortical fibroblasts from cats with azotaemic CKD (CKD-FCF). This evidence concerns the gene TGFB1 and chronic kidney disease.