Palbociclib is an investigational drug. An investigational drug is a medication that has not been approved for marketing by the Food and Drug Administration (FDA). Palbociclib blocks a protein called CDK4 which is part of a pathway in liposarcoma cells that is over-active. The investigators hope that blocking CDK4 will shut down this pathway in the liposarcoma cells and stop tumors from growing. Palbociclib is an oral medication.