PD-0332991 is an investigational or experimental anti-cancer agent that has not yet been approved by the Food and Drug Administration for use in colorectal cancer. It is given as a pill which is taken once a day for one week followed by one week off. 5-Fluorouracil and Oxaliplatin are administered as an infusion into a vein once every 2 weeks and are approved for and used as chemotherapy for several cancers.