RNA sequencing (RNA-Seq) and confirmatory expression studies in our laboratories demonstrated robust expression of FOXI1 and its downstream targets, including H+-ATPase and cytoplasmic carbonic anhydrase 2 (CAII), in the cyst epithelia of Tsc1 (or Tsc2) knockout (KO) mice, but not in Pkd1 mutant mice (Barone et al., 2021; Barone et al., 2023). The gene discussed is FOXI1; the disease is cyst.