To determine whether other nephron segments or tubular cells contribute to cyst epithelium, we performed double labeling with the Na+:HCO3− cotransporter NBC‐e1 (red fluorescence), which primarily labels the basolateral membrane of proximal tubule and thick ascending limb of Henle (TALH), and H+‐ATPase (green fluorescence), which is strongly expressed in intercalated cells. Here, SLC4A4 is linked to cyst.