KCNN4 and sickle cell disease: Senicapoc is a potent and selective inhibitor of KCa3.1 developed for the treatment of sickle cell anemia [half maximal inhibitory concentration (IC50) = 11 nM; screening of 57 targets yielded no hits below 1 μM other than KCa3.1] (Ataga et al., 2006; Ataga et al., 2008; Ataga and Stocker, 2009; Dale et al., 2016; Staal et al., 2017a).