Multiple PK blood samples will be taken from Days 1-4 and Days 15-18. Gleevec® PK will be assessed after oral administration of 400 mg Gleevec® alone, and after oral administration of 400 mg Gleevec® with concomitant administration of 4000 mg calcium carbonate. Two 10-hour outpatient dosing visits and six brief outpatient visits are required to accommodate all study procedures.