PKD1 and autosomal dominant polycystic kidney disease: The PC1-CTT is a focal point in ADPKD research due to the pathological high abundance of its cleavage products, such as the ∼30 kDa (PC1-p30) and ∼15 kDa (PC1-p15) fragments, in ADPKD kidneys and nonorthologous mouse models of polycystic kidney disease (PKD) (6, 7).