RI-BPI has no antilymphoma activity in the Toledo xenograft. (A) Tumor growth plot in Toledo (an OxPhos-type cell line) xenografted mice treated with control peptide (●) or RI-BPI 500 μg/day () for 10 consecutive days. The y-axis represents the percentage of tumor volume (in mm³) compared with day 1 of treatment, and the x-axis represents treatment day. (B) Tumor burden (in milligrams) at day 10 in control peptide (■) and RI-BPI 500 μg/day () treated Toledo mice. (C) Serum levels of human β2-microglobulin (in micrograms per milliliter) at day 10 in control peptide (■) and RI-BPI 500 μg/day () treated Toledo mice. (D) Representative images from Toledo mice tumors after being treated with control peptide (first column) or RI-BPI 500 μg/day (second column), and assayed for apoptosis by TUNEL. The plot on the far right represents the apoptotic index (apoptotic cells over total cells) with the percentage of apoptotic cells in the y-axis for control peptide (■) and RI-BPI 500 μg/day (). Slides were mounted with permanent mounting medium (Vectamount; Vector Laboratories). Slides were viewed with a light microscope (AxioSkop 2; Carl Zeiss) using a Plan-neofluar lens at a 10×/0.50 air objective, a 25×/0.80 oil objective, a 40×/0.90 oil objective, and a 100×/1.30 oil objective. Images were acquired using a color camera (AxioCam; Carl Zeiss), processed using Axiovision software (Carl Zeiss), and scored using ImageJ software (National Institutes of Health, Bethesda, MD).