This will be an open-label, single-center study to evaluate the mass-balance and pharmacokinetics of PD-0332991 in approximately 6 healthy male subjects receiving a single oral 125 mg dose of PD-0332991 containing approximately 100 microcuries of [14C]-PD-0332991. Subjects will be checked in to the research unit from approximately 12 hours prior to dosing and remain in house until greater than 90% of the administered radioactivity is collected from bodily excreta or until less than 1% of the administered radioactivity is recovered from excreta on consecutive days. This study will investigate the extent of involvement of the renal and hepatic systems in the elimination of PD-0332991 and will seek to identify the compound's major metabolites.

Inclusion Criteria:

• A Healthy Male Volunteer between 18 and 55 years of age inclusive
• A Body Mass Index (BMI) of 17.5 to 30.5 kg/m2 and a total body weight >50kg
• A signed informed consent document

Exclusion Criteria:

• Evidence or history of clinically significant hematological, renal, endocrine, pulmonary, gastrointestinal, cardiovascular,hepatic,psychiatric, neurologic, or allergic disease.
• A positive urine drug or urine cotinine screen.
• Concurrent use of herbal or prescription medications or treatment with an investigational drug within 30 days or 5 half-lives preceding first dose of study medication.
• Subjects whose occupation requires exposure to radiation or monitoring of radiation exposure.
• Subjects with a history of irregular bowel movements (eg, regular episodes of diarrhea or constipation, irritable bowel syndrome (IBS) or lactose intolerance).