Metals present in CSE regulate CFTR expression. 16HBE14o- cells were incubated with 10% CSE before and after incubation with Chelex-100 beads, in absence or presence of 10 μM cadmium chloride. CFTR protein was detected by immunoblotting 48 hours after treatment. Blots are representative of at least three independent experiments. *p < 0.05.