Table 3 shows the small molecule positive and negative modulators with differential KCa2 subtype selectivity [44]. For treating CF and other mucociliary diseases, KCa3.1 inhibitors are needed [5]. Senicapoc [95] and TRAM-34 [96] inhibit KCa3.1 channels with IC50 values of ~11 nM, and ~20 nM, respectively, and they are highly selective for KCa3.1 channels over KCa2 channel subtypes [33]. The selective negative modulator for the KCa2 channel AP14145 is equipotent in inhibiting KCa2.2 and KCa2.3 but is ineffective on KCa3.1 channels [97]. This evidence concerns the gene KCNN4 and cystic fibrosis.