In CF hAECs Cl−, secretion was measured by the Isc response to forskolin (Fsk) and the CFTR potentiator, P5, as well as the total Isc inhibited by the specific CFTR inhibitor, CFTRInh172 (172), after first inhibiting sodium transport by ENaC with amiloride (Figure 8D, left panel). The gene discussed is CFTR; the disease is cystic fibrosis.