Furthermore, in these experiments and additional experiments performed on non-CF epithelia bathed in nominally Cl–-free solutions, IL-13 did not affect amiloride-sensitive Isc values, suggesting that the large increase in Cl– channel function produced the difference in amiloride-sensitive Isc observed after treatment of non-CF epithelia with IL-13 (Supplemental Figure 1, A–D). Here, IL13 is linked to cystic fibrosis.