Kaplan-Meier estimates of overall survival of mice bearing human lymphoma xenografts. (A) DHL-4. (B) FL-18. Mice were treated for 4 weeks with 4HPR (250 μg/d, 5 days per week), rituximab (200 μg/wk), fenretinide + rituximab (at the noted doses), or control with no drug (solvent only). Survival was measured from the time of initiating therapy.