Methods for therapy of cystic fibrosis and other conditions such as cancer are provided. The methods comprise one or more agents capable of increasing thiol-containing compound transport via a transporter system (i.e. ABC transporters such as MDR-1 or MRP-2) in cells. Other embodiments include the use of agents to modulate transport of thiol-containing compounds within the cell. Therapeutic methods involve the administration of such agents to a patient afflicted with cystic fibrosis, cancer and/or another condition responsive to stimulation of thiol-containing compound transport.