CCL21 and polycystic kidney disease: Furthermore, the CFTR (cystic fibrosis transmembrane conductance regulator), the Ca2+-activated chloride channels TMEM16A (Anoctamin 1), but also the SLC member Slc12a2 have been identified as crucial aggravating co-factors for cyst enlargement in polycystic kidney disease (Magenheimer et al., 2006; Cabrita et al., 2020).