CYS1 and cystic kidney disease: Further studies are required to test this hypothesis in vivo, including a careful analysis of the potential for Cys1 transgene overexpression to confer partial or complete rescue of the renal cystic phenotype in Tfap2b−/− mice, as was previously demonstrated for Cys1 transgene rescue of renal cystic disease in Cys1cpk/cpk (cpk) mice (Yang et al., 2021).