 This study will investigate the safety and efficacy of an investigational drug, PF-04171327 on the signs and symptoms of rheumatoid arthritis in patients that require glucocorticoids while on background methotrexate. This study will also look at the response of chemical and biological markers in rheumatoid arthritis patients. Lastly, this study will measure the PK amount of drug in the blood of methotrexate while patients may be taking PF-04171327. 