This will be a 6 cohort study investigating one experimental formulation of palbociclib in each of the six cohorts of 10 healthy subjects. Each cohort will receive two treatments in a fixed-sequence. In Period 1, all subjects will receive a single 125mg dose of palbociclib alone and undergo serial pharmacokinetic blood sampling for up to 120 hours post-dose. In Period 2, all subjects will receive daily 40mg doses of Rabeprazole for 7 consecutive days, and approximately 4 hours after the Day 7 rabeprazole dose each subject will receive a single 125mg dose of palbociclib. Subjects will undergo serial pharmacokinetic blood sampling up to 120 hours post-dose.