SLC22A3 and cystic fibrosis: To see whether we could extend these findings to pharmacochaperones, we pre-treated the wildtype and variants with the steroid hormones progesterone and corticosterone, inhibitors of OCT3; ibogaine, which has been shown to enhance serotonin and dopamine transporter expression [41]; ivacaftor, a pharmacochaperone used in the treatment of cystic fibrosis [35]; and metformin, an antidiabetic biguanide and substrate of OCT3 (Figure 3D–F).