The CD-PC-Fibrotic cells were the dominant cell subtype in Pkd1 HOMO-21 kidneys compared to Pkd1 HET-21 kidneys, which may guide us to further understand the epithelial–mesenchymal transition (EMT) process, a widely accepted mechanism by which injured renal tubular cells transform into mesenchymal cells that contribute to the development of fibrosis in chronic renal failure. The gene discussed is PKD1; the disease is chronic kidney disease.