Design: The study is open-label, dose escalation, safety and proof of principle study of the combination of intravenous abciximab and reteplase. A fixed dose of abciximab will be used in all patients: 0.25 mg/kg bolus (to a maximum of 30 mg) followed by a 0.125 microgram/kg/minute infusion (to a maximum of 10.0 microgram/minute) for 12 hours. The five dosing groups for the reteplase dose are 0 U, 2.5 U, 5.0 U, 7.5 U, and 10.0 U. A maximum of 72 patients will be treated using an adaptive statistical design, in which data on both the response and toxicity will be used to determine the dose for subsequent patients, thereby minimizing exposure to either ineffective or toxic doses. Non-investigational patient management will be standardized across all patients according to the NIH Stroke Center Clinical Care Pathway.