The goal of this project is to investigate how the open channel blocker, GlyH-101 binds to the CFTR channel. Dose-response experiments tell us the pharmacodynamics of this drug candidate for secretory diarrhea. GlyH-101 blocks the pore of CFTR from the extracellular side. It does not get through the CFTR channel. Does either mutagenesis (L102C or R104C) affect the binding of GlyH-101 to CFTR? The voltage-dependence of GlyH-101 block needs to be analyzed using SigmaPlot (see the protocol)