KCNN4 and cystic fibrosis: Surprisingly, CftrΔF508/ΔF508/Kcnn4−/− mice survived significantly better than the CftrΔF508/ΔF508 mice (Fig. 1A), consistent with the idea that Kcnn4 is indeed a modifier gene for CF but suggesting an ameliorating effect of its inactivation rather than the aggravating effect expected from a straightforward mechanism involving its role in anion secretion.