IGFBP7 inhibits IGF1R internalization on insulin stimulation. (A) Cell surface expression of the INSR and IGF1R in a representative case of serum-starved primary BCP-ALL (B1042) cells after 15 minutes or 4 hours of treatment with insulin (500 ng/mL), IGFBP7 (100 ng/mL), anti-IGFBP7 (clone C311, 20 µg/mL), or associations, as measured by flow cytometry analysis. The anti-IGFBP7 antibody (clone C311) was added 30 minutes before insulin/IGFBP7 addition. (B) Normalized results from 4 different primary BCP-ALL (B1042 and B1421) and T-ALL (T1238 and T1260) cells, according to the times and treatments described above. A histogram overlay was used to calculate the percentage of labeled cells with respect to cells left untreated (Starved). See also supplemental Figure 10. Statistical analysis was done by 1-way ANOVA and Bonferroni posttests (****P .0001).